CA2876566A1 - Anodic oxidation of organic substrates in the presence of nucleophiles - Google Patents
Anodic oxidation of organic substrates in the presence of nucleophiles Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B3/00—Electrolytic production of organic compounds
- C25B3/20—Processes
- C25B3/23—Oxidation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D317/00—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms
- C07D317/08—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3
- C07D317/10—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings
- C07D317/32—Heterocyclic compounds containing five-membered rings having two oxygen atoms as the only ring hetero atoms having the hetero atoms in positions 1 and 3 not condensed with other rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
- C07D317/34—Oxygen atoms
- C07D317/36—Alkylene carbonates; Substituted alkylene carbonates
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B3/00—Electrolytic production of organic compounds
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B3/00—Electrolytic production of organic compounds
- C25B3/01—Products
Abstract
This invention refers to a process of anodic substitution comprising the electrolyzing the liquid reaction medium in an electrochemical cell comprising a cathode and an anode, whereas the liquid reaction medium comprises an organic compound with at least one carbon bound hydrogen atom, a nucleophilic agent, and an ionic liquid in a proportion of at least 10 % by weight, and whereas the said hydrogen atoms are replaced at least partially with the nucleophilic group of said nucleophilic agent. Preferably, a gas diffusion layer electrode is used as anode.
Description
Anodic oxidation of organic substrates in the presence of nucleophiles Description This invention refers to a process of anodic substitution comprising electrolyzing the liquid reac-tion medium in an electrochemical cell comprising a cathode and an anode, whereas the liquid reaction medium comprises an organic compound with at least one carbon bound hydrogen atom, a nucleophilic agent, and an ionic liquid in a proportion of at least 10 % by weight, and whereas the said hydrogen atoms are replaced at least partially with the nucleophilic group of said nucleophilic agent. In a preferred embodiment of the invention, a gas diffusion layer elec-trode is used as anode. Preferred nucleophilic agents are aliphatic alcohols and aliphatic car-boxylic acids. Preferred ionic liquids are quaternary ammonium compounds having a melting point of less than 200 C at atmospheric pressure (1 bar).
The anodic oxidation (in the context of this invention also referred to as electrochemical oxida-tion) of a substrate in the presence of nucleophile is an important reaction type in organic elec-trochemistry which allows for an anodic substitution. Different nucleophiles are used in this syn-thetic valuable electrolysis (Eberson & Nyberg, Tetrahedron 1976, 32, 2185).
With alcanols like methanol an alkoxylation of a substrate can be carried out (EP 1348043 B, EP
1111094 A).
With acids like HCOOH, CH3COOH or CF3COOH an acyloxylation of a substrate is possible (EP
1111094 A). Also the fluorination is known as one way for a selective introduction of fluorine.
(Fuchigami, Organic Electrochemistry, 4th edn., (Eds.: Lund & Hammerich), Dekker, New York, 2001, p. 1035). In general this anodic substitution works nicely if the first step the removal of an electron from the substrate renders a stable enough cation radical so that an attack of a nucleo-phile can lead to the substituted product.
Anodic substitution is used at industrial scale for example in the double methoxylation of me-thylsubstituted aromatic compounds leading to the corresponding acetals. The first methoxyla-tion step renders the ether as intermediate and the following methoxylation leads to the acetal in one cell/process. By this elegant way aromatic aldehydes are synthesized from toluene deriva-tives like p-tert-butyl benzaldehyde from p-tert-butyl toluene (DE 2848397).
But there are also drawbacks to this electrosynthesis which is shown for example in the limited substrate range for the acetalization of methylsubstituted aromatic compounds.
The acetaliza-tion of p-substituted toluene derivatives is only successful if the substituent is electron pushing like the tert-butyl group in the industrial example above. Though if the p-substituent is non elec-tron pushing the selectivity is very low. This problem was not solved in decades.
Also an obvious problem for an anodic substitution is if the reaction of the nucleophile with the substrate follows an undesired reaction path, e.g. cyclic compounds like ethylene carbonate react with nucleophiles under ring opening. Therefore a substitution at the ethylene carbonate ring generally has not been carried out by a nucleophilic but a radical pathway.
Unexpectedly, a method was found to improve anodic substitution in general (conversion rate, selectivity, current yield and accessibility of a broad range of organic compounds for anodic substitution) by use high ionic liquid electrolyte concentration.
This method also allows for anodic substitution of organic compounds which are prone to nu-cleophilic side reactions such as the ring-opening reaction of cyclic carbonates.
The invention provides a process of anodic substitution comprising the steps of:
The anodic oxidation (in the context of this invention also referred to as electrochemical oxida-tion) of a substrate in the presence of nucleophile is an important reaction type in organic elec-trochemistry which allows for an anodic substitution. Different nucleophiles are used in this syn-thetic valuable electrolysis (Eberson & Nyberg, Tetrahedron 1976, 32, 2185).
With alcanols like methanol an alkoxylation of a substrate can be carried out (EP 1348043 B, EP
1111094 A).
With acids like HCOOH, CH3COOH or CF3COOH an acyloxylation of a substrate is possible (EP
1111094 A). Also the fluorination is known as one way for a selective introduction of fluorine.
(Fuchigami, Organic Electrochemistry, 4th edn., (Eds.: Lund & Hammerich), Dekker, New York, 2001, p. 1035). In general this anodic substitution works nicely if the first step the removal of an electron from the substrate renders a stable enough cation radical so that an attack of a nucleo-phile can lead to the substituted product.
Anodic substitution is used at industrial scale for example in the double methoxylation of me-thylsubstituted aromatic compounds leading to the corresponding acetals. The first methoxyla-tion step renders the ether as intermediate and the following methoxylation leads to the acetal in one cell/process. By this elegant way aromatic aldehydes are synthesized from toluene deriva-tives like p-tert-butyl benzaldehyde from p-tert-butyl toluene (DE 2848397).
But there are also drawbacks to this electrosynthesis which is shown for example in the limited substrate range for the acetalization of methylsubstituted aromatic compounds.
The acetaliza-tion of p-substituted toluene derivatives is only successful if the substituent is electron pushing like the tert-butyl group in the industrial example above. Though if the p-substituent is non elec-tron pushing the selectivity is very low. This problem was not solved in decades.
Also an obvious problem for an anodic substitution is if the reaction of the nucleophile with the substrate follows an undesired reaction path, e.g. cyclic compounds like ethylene carbonate react with nucleophiles under ring opening. Therefore a substitution at the ethylene carbonate ring generally has not been carried out by a nucleophilic but a radical pathway.
Unexpectedly, a method was found to improve anodic substitution in general (conversion rate, selectivity, current yield and accessibility of a broad range of organic compounds for anodic substitution) by use high ionic liquid electrolyte concentration.
This method also allows for anodic substitution of organic compounds which are prone to nu-cleophilic side reactions such as the ring-opening reaction of cyclic carbonates.
The invention provides a process of anodic substitution comprising the steps of:
a) providing an organic compound comprising at least one hydrogen atom bound to a car-bon atom;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound and a nucleophilic agent;
c) electrolyzing the liquid reaction medium to cause replacement of at least a part of said hydrogen atoms with the nucleophilic group of the nucleophilic agent, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
The process of anodic substitution is special case of electrochemical oxidation.
It is a critical feature of the process according to the invention to employ a liquid reaction medi-um that comprises ionic liquid in a proportion of at least 10 % by weight.
In the context of the present invention, the term ionic liquid refers to salts (compounds of cations and anions) which at atmospheric pressure (1 bar) have a melting point of less than 200 C, preferably less than 150 C, particularly preferably less than 100 C.
Possible ionic liquids also include mixtures of different ionic liquids.
Preferred ionic liquids comprise an organic compound as cation (organic cation). Depending on the valence of the anion, the ionic liquid can comprise further cations, including metal cations, in addition to the organic cation. The cations of particularly preferred ionic liquids are exclusively an organic cation or, in the case of polyvalent anions, a mixture of different organic cations.
Suitable organic cations comprise, in particular, heteroatoms such as nitrogen, sulfur, oxygen or phosphorus; in particular, the organic cations comprise an ammonium group (ammonium cati-ons), an oxonium group (oxonium cations), a sulfonium group (sulfonium cations) or a phos-phonium group (phosphonium cations).
In a particular embodiment, the organic cations of the ionic liquids are ammonium cations, which for the present invention are - non-aromatic compounds having a localized positive charge on the nitrogen atom, e.g.
compounds having tetravalent nitrogen (quaternary ammonium compounds) or - compounds having trivalent nitrogen, with one bond being a double bond, or - aromatic compounds having a delocalized positive charge and at least one nitrogen at-om, preferably from one to three nitrogen atoms, in the aromatic ring system.
Preferred organic cations are quaternary ammonium cations, preferably those having three or four aliphatic substituents, particularly preferably C1-C12-alkyl groups, on the nitrogen atom; the-se aliphatic substituents may optionally be substituted by hydroxyl groups.
In the context of the present invention, the expression C1-C12-alkyl comprises straight-chain or branched and saturated or unsaturated C1-C12-alkyl groups. Preferably, the C1-C12-alkyl groups are saturated.
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound and a nucleophilic agent;
c) electrolyzing the liquid reaction medium to cause replacement of at least a part of said hydrogen atoms with the nucleophilic group of the nucleophilic agent, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
The process of anodic substitution is special case of electrochemical oxidation.
It is a critical feature of the process according to the invention to employ a liquid reaction medi-um that comprises ionic liquid in a proportion of at least 10 % by weight.
In the context of the present invention, the term ionic liquid refers to salts (compounds of cations and anions) which at atmospheric pressure (1 bar) have a melting point of less than 200 C, preferably less than 150 C, particularly preferably less than 100 C.
Possible ionic liquids also include mixtures of different ionic liquids.
Preferred ionic liquids comprise an organic compound as cation (organic cation). Depending on the valence of the anion, the ionic liquid can comprise further cations, including metal cations, in addition to the organic cation. The cations of particularly preferred ionic liquids are exclusively an organic cation or, in the case of polyvalent anions, a mixture of different organic cations.
Suitable organic cations comprise, in particular, heteroatoms such as nitrogen, sulfur, oxygen or phosphorus; in particular, the organic cations comprise an ammonium group (ammonium cati-ons), an oxonium group (oxonium cations), a sulfonium group (sulfonium cations) or a phos-phonium group (phosphonium cations).
In a particular embodiment, the organic cations of the ionic liquids are ammonium cations, which for the present invention are - non-aromatic compounds having a localized positive charge on the nitrogen atom, e.g.
compounds having tetravalent nitrogen (quaternary ammonium compounds) or - compounds having trivalent nitrogen, with one bond being a double bond, or - aromatic compounds having a delocalized positive charge and at least one nitrogen at-om, preferably from one to three nitrogen atoms, in the aromatic ring system.
Preferred organic cations are quaternary ammonium cations, preferably those having three or four aliphatic substituents, particularly preferably C1-C12-alkyl groups, on the nitrogen atom; the-se aliphatic substituents may optionally be substituted by hydroxyl groups.
In the context of the present invention, the expression C1-C12-alkyl comprises straight-chain or branched and saturated or unsaturated C1-C12-alkyl groups. Preferably, the C1-C12-alkyl groups are saturated.
Preference is likewise given to organic cations which comprise a heterocyclic ring system hav-ing from one to three, in particular one or two, nitrogen atoms as constituents of the ring system.
Monocyclic, bicyclic, aromatic or nonaromatic ring systems are all possible.
Mention may be made by way of example of bicyclic systems as described in WO 2008/043837. The bicyclic systems of WO 2008/043837 are diazabicyclo derivatives, preferably formed by a 7-membered ring and a 6-membered ring, which comprise an amidinium group; particular mention may be made of the 1,8-diazabicyclo(5.4.0)undec-7-enium cation.
Particularly preferred ammonium cations are quaternary ammonium cations, imidazolium cati-ons, pyrimidinium cations and pyrazolium cations.
The ionic liquids can comprise inorganic or organic anions. Such anions are described, for ex-ample, in the abovementioned WO 03/029329, WO 2007/076979, WO 2006/000197 and WO
2007/128268.
Preference is given to anions from the group of alkylsulfates of the formula Ra0503-, where Ra is a C1-C12-alkyl group, a perfluorinated C1-C12-alkyl group, or a C6-Cio-aryl group, preferably a C1-C6-alkyl group, a perfluorinated C1-C6-alkyl group, or a Cs-aryl group (tosylate);
alkylsulfonates of the formula Ra503-, where Ra is a C1-C12-alkyl group, preferably a C1-C6-alkyl group;
bisalkylsulfonylimides of the formula(Ra502)2N-, where Ra is a C1-C12-alkyl group or a perfluorinated C1-C12-alkyl group, preferably a C1-C6-alkyl group or a perfluorinated C1-C6-alkyl group;
halides, in particular chloride, bromide or iodide;
pseudohalides such as thiocyanate, dicyanamide;
carboxylates of the formula Ra000-, where Ra is a C1-C12-alkyl group, preferably a C1-C6-alkyl group, in particular acetate;
phosphates, in particular the dialkyl phosphates of the formula RaRbPO4-, where Ra and Rb are each, independently of one another, a C1-C6-alkyl group;
in particu-lar, Ra and Rb are the same alkyl group (e.g. dimethyl phosphate or diethyl phosphate);
and phosphonates, in particular monoalkyl phosphonates of the formula RaP03-, where Ra is a C1-C6-alkyl group.
Suitable ionic liquids in the context of the present invention are e.g.
ammoniumtetraalkyl alkyl-sulfate (such as methyltributylammonium methylsulfate (MTBS)) or ammoniumtetraalkyl bis(alkylsulfonyl)imide (such as methyltributylammonium bis(trifluoromethylsulfonyl)imide (MTB-TFSI) or tetraoctylammonium bis(trifluoromethylsulfonyl)imide).
The proportion of the ionic liquid or the mixture thereof should be high at least 10 % by weight, preferably at least 25 % by weight, more preferably at least 50 % by weight, particularly at least 65 % by weight based on the entire liquid reaction medium.
As anode and cathode any electrode suitable for electrochemical oxidation processes can be used. A person skilled in the art can determine which electrode is suitable.
Monocyclic, bicyclic, aromatic or nonaromatic ring systems are all possible.
Mention may be made by way of example of bicyclic systems as described in WO 2008/043837. The bicyclic systems of WO 2008/043837 are diazabicyclo derivatives, preferably formed by a 7-membered ring and a 6-membered ring, which comprise an amidinium group; particular mention may be made of the 1,8-diazabicyclo(5.4.0)undec-7-enium cation.
Particularly preferred ammonium cations are quaternary ammonium cations, imidazolium cati-ons, pyrimidinium cations and pyrazolium cations.
The ionic liquids can comprise inorganic or organic anions. Such anions are described, for ex-ample, in the abovementioned WO 03/029329, WO 2007/076979, WO 2006/000197 and WO
2007/128268.
Preference is given to anions from the group of alkylsulfates of the formula Ra0503-, where Ra is a C1-C12-alkyl group, a perfluorinated C1-C12-alkyl group, or a C6-Cio-aryl group, preferably a C1-C6-alkyl group, a perfluorinated C1-C6-alkyl group, or a Cs-aryl group (tosylate);
alkylsulfonates of the formula Ra503-, where Ra is a C1-C12-alkyl group, preferably a C1-C6-alkyl group;
bisalkylsulfonylimides of the formula(Ra502)2N-, where Ra is a C1-C12-alkyl group or a perfluorinated C1-C12-alkyl group, preferably a C1-C6-alkyl group or a perfluorinated C1-C6-alkyl group;
halides, in particular chloride, bromide or iodide;
pseudohalides such as thiocyanate, dicyanamide;
carboxylates of the formula Ra000-, where Ra is a C1-C12-alkyl group, preferably a C1-C6-alkyl group, in particular acetate;
phosphates, in particular the dialkyl phosphates of the formula RaRbPO4-, where Ra and Rb are each, independently of one another, a C1-C6-alkyl group;
in particu-lar, Ra and Rb are the same alkyl group (e.g. dimethyl phosphate or diethyl phosphate);
and phosphonates, in particular monoalkyl phosphonates of the formula RaP03-, where Ra is a C1-C6-alkyl group.
Suitable ionic liquids in the context of the present invention are e.g.
ammoniumtetraalkyl alkyl-sulfate (such as methyltributylammonium methylsulfate (MTBS)) or ammoniumtetraalkyl bis(alkylsulfonyl)imide (such as methyltributylammonium bis(trifluoromethylsulfonyl)imide (MTB-TFSI) or tetraoctylammonium bis(trifluoromethylsulfonyl)imide).
The proportion of the ionic liquid or the mixture thereof should be high at least 10 % by weight, preferably at least 25 % by weight, more preferably at least 50 % by weight, particularly at least 65 % by weight based on the entire liquid reaction medium.
As anode and cathode any electrode suitable for electrochemical oxidation processes can be used. A person skilled in the art can determine which electrode is suitable.
In a preferred embodiment of the invention, at least one gas diffusion layer electrode is em-ployed as anode.
Gas diffusion layer (GDL) electrodes are known from fuel cell technology and consist of a sub-strate and a microporous layer containing carbon particles as main component.
Suitable GDLs are described inter alia in US 4,748,095, US 4,931,168 and US 5,618,392. The teaching of those documents is incorporated herein by reference. Suitable GDLs are commercial available e.g. from Ballard Power Systems Inc., Freudenberg FOOT KG (e.g. the g. of the H2315 series) or SGL Group.
A GDL generally comprises a fibre layer or substrate and a microporous layer (MPL) consisting of carbon particles attached to each other. The degree of hydrophobization can vary in such a way that wetting and gas permeability can be adjusted.
GDL electrodes for the process of the invention preferably do not contain a catalyst supported on the surface of the electrode.
GDL electrodes for the process of the invention contain a substrate and a microporous layer containing carbon particles preferable carbon black as main component.
GDL electrodes for the process of the invention can be manufactured according to US
6,103,077, eventually using commercially available components like substrate and carbon parti-cles.
Preferably, the cathode is selected from Pt, Pb, Ni, graphite, felt materials like coal or graphite felts, stainless steel and GDL electrodes.
The organic compound provided in step a) of process according to the present invention can generally be any organic compound that comprises at least one hydrogen atom directly bound to a carbon atom that can be substituted by a nucleophilic group under the conditions of the anodic substitution. It is of course also possible to employ a mixture of organic compounds.
Suitable are organic compounds that in combination with at least one nucleophilic agent, with ionic liquid in a proportion of at least 10 % by weight and optionally with solvents and/or addi-tives allow the formation of a liquid reaction medium with ionic conductivity so that electrolysis can be applied to cause the anodic substitution.
Preferably, the hydrogen atom is directly bound to a carbon atom is part of an alkyl group, more preferably. According to the invention 1, 2 or 3 hydrogen atoms are directly bound to said car-bon atom. Preferably, said carbon atom is a tertiary carbon atom of an alkane or a cycloalkane, an allylic carbon atom of an alkene or a cycloalkene or corresponding diens, a carbon atom in a-position to the arene moiety of an alkylarene, a carbon atom in a-position to the nitrogen atom of an amide, or a carbon atom in a-position to the oxygen atom of an ether.
Preferably, the organic compound according to the invention exhibits an alkyl or alkylen group having at least one hydrogen atom directly bound to a carbon atom.
Particularly preferred or-ganic compounds are (i) alkanes or cycloalkanes having at least one hydrogen atom directly bound to a tertiary carbon atom, (ii) alkenes or cycloalkenes or corresponding dienes having at least one hydrogen atom directly bound to an allylic carbon atom, (iii) alkylarenes having at least one hydrogen atom directly bound to a carbon atom in a-position to the arene moiety, (iv) amides having at least one hydrogen atom directly bound to a carbon atom in a-position to the nitrogen atom, or (v) ethers, esters, carbonates or acetals having at least one hydrogen atom directly bound to a carbon atom in a-position to the oxygen atom.
The organic compound can comprise functional groups that are essentially stable under the reaction conditions. Suitable functional groups comprise carbonyl, thiocarbonyl, ester, thioester, 5 amide, oxycarbonyloxy, urethane, urea, hydroxyl, sulfonyl, sulfinate, sulfonate, sulfate, ether, amine, nitrile, etc. and combinations thereof.
In one embodiment of the present invention, the organic compound provided in step a) is se-lected from compounds of the general formula I
,1 ,2 I-< 1-<
X 0 (I) wherein X is 0, N-R3 or CR4R5, R1 is selected from C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, formyl, C1-C6-alkylcarbonyl and Ci-C6-alkyloxycarbonyl, wherein R1 may also be C1-C6-alkoxy if X is a CR4R5 group, wherein R1 may also be Ci-C6-alkylcarbonyloxy if X is a N-R3 or CR4R5 group, R2 is selected from hydrogen, Ci-C6-alkyl, Ci-C6-alkoxy-Ci-C6-alkyl, C6-Cio-aryl-Ci-C6-alkyl, C3-C12-cycloalkyl and C6-Cio-aryl, R3 is selected from hydrogen, Ci-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, formyl, 01-06-alkylcarbonyl and C1-C6-alkyloxycarbonyl, R4 and R5 are independently selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl and C1-C6-alkoxy, or R1 and R2 together with the X-(C=0)-0 group to which they are bound form a 5- to 7-membered heterocyclic ring, which may contain at least one additional heteroatom or het-eroatom containing group, selected from 0, S, NRc or 0=0, wherein Rc is selected from hydrogen, alkyl, cycloalkyl and aryl, or X is a CR4R5 group and R1 and R4 together with the carbon atom to which they are bound form a 3 to 7 membered carbocyclic ring.
Preferably, X is 0, CH2 or NR3, wherein R3 is 01-04-alkyl or Ci-04-alkylcarbonyl.
In a preferred embodiment, R1 and R2 together with the X-(C=0)-0 group to which they are bound form a 5 to 7 membered heterocyclic ring, which may contain at least one additional het-eroatom or heteroatom containing group, selected from 0, S, NRc or 0=0, wherein Rc is select-ed from hydrogen, alkyl, cycloalkyl or aryl. In this embodiment, X is preferably 0, CH2 or NR3, wherein R3 is 01-04-alkyl or Ci-04-alkylcarbonyl. Further, in this embodiment R1 and R2 together are selected from groups of the formulae -0H2-0H2-, -0H2-0H2-0H2- and -CH(CxH2,0-1)-CH2-, wherein xis 1, 2, 3 or 4.
In a further preferred embodiment, the organic compound provided in step a) is selected from compounds of the general formula la xX
\
A ( R6 H
(la) wherein X is 0, CH2 or NR3, wherein R3 is 01-C4-alkyl or 01-04-alkylcarbonyl, A is an alkylene group selected from -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CHR7-, -CHR7-CH2-, -CH2-CHR7-, -CHR7-CH2-CH2-, -CH2-CHR7-CH2-, and -CH2-CH2-CHR7-, wherein R7is Ci-Cs-alkyl, R6 is hydrogen or 01-C6-alkyl.
Preferably, X is 0 or -CH2-, A is -CH2- or -CHR7-, wherein R7 is 01-04-alkyl, and R6 is hydrogen or Ci-C4-alkyl.
Examples of suitable organic compounds of the general formulas I and la are ethylene car-bonate, propylene carbonate (4-methyl-1,3-dioxolan-2-one) and gamma butyrolactone.
In one embodiment of the present invention, the organic compound provided in step a) is se-lected from compounds of the general formula II
Z-CHR8R9 (II) wherein Z is selected from 06-010-aryl, substituted 06-010-aryl, 01-06-allyl, -NR10R11 group, and 01-06-alkoxy, R8 is selected from hydrogen, 01-06-alkyl, 01-06-alkoxy-01-06-alkyl, wherein R8 may also be 01-06-alkoxy if Z is a 06-C10-aryl or 01-06-allyl, R9 is selected from hydrogen, 01-06-alkyl, 01-06-alkoxy, 01-06-alkoxy-01-06-alkyl, 06-010-aryl, substituted 06-010-aryl, 06-Cio-aryl-C1-06-alkyl, and 03-012-cycloalkyl, or R8 and R9 together form a 04-07-alkylen or a 04-07-alkenylen, and R1 and R" are independently selected from hydrogen, 01-06-alkyl, 06-010-aryl, substituted 06-Cio-aryl, and 01-06-alkylcarbonyl or wherein Z, Wand R9 are independently a 01-06-alkyl.
Preferably, Z is 06-C10-aryl or substituted 06-010-aryl, and R8 and R9 areindependently selected from hydrogen, 01-06-alkyl and 01-06-alkoxy, particularly preferably, Z is 06-C10-aryl or substi-tuted 06-010-aryl, and Wand R9 areindependently selected from hydrogen, 01-04-alkyl and 01-04-alkoxy.
Also preferably, Z is 01-06-alkoxy, R8 is selected from hydrogen and 01-06-alkyl, and R9 is se-lected from hydrogen, 01-06-alkyl, 01-06-alkoxy, 06-010-aryl, and substituted 06-010-aryl, par-ticularly preferably, Z is 01-04-alkoxy, R8 is selected from hydrogen and 01-04-alkyl, and R9 is selected from hydrogen, 01-04-alkyl, 01-04-alkoxy, 06-010-aryl, and substituted 06-010-aryl.
Gas diffusion layer (GDL) electrodes are known from fuel cell technology and consist of a sub-strate and a microporous layer containing carbon particles as main component.
Suitable GDLs are described inter alia in US 4,748,095, US 4,931,168 and US 5,618,392. The teaching of those documents is incorporated herein by reference. Suitable GDLs are commercial available e.g. from Ballard Power Systems Inc., Freudenberg FOOT KG (e.g. the g. of the H2315 series) or SGL Group.
A GDL generally comprises a fibre layer or substrate and a microporous layer (MPL) consisting of carbon particles attached to each other. The degree of hydrophobization can vary in such a way that wetting and gas permeability can be adjusted.
GDL electrodes for the process of the invention preferably do not contain a catalyst supported on the surface of the electrode.
GDL electrodes for the process of the invention contain a substrate and a microporous layer containing carbon particles preferable carbon black as main component.
GDL electrodes for the process of the invention can be manufactured according to US
6,103,077, eventually using commercially available components like substrate and carbon parti-cles.
Preferably, the cathode is selected from Pt, Pb, Ni, graphite, felt materials like coal or graphite felts, stainless steel and GDL electrodes.
The organic compound provided in step a) of process according to the present invention can generally be any organic compound that comprises at least one hydrogen atom directly bound to a carbon atom that can be substituted by a nucleophilic group under the conditions of the anodic substitution. It is of course also possible to employ a mixture of organic compounds.
Suitable are organic compounds that in combination with at least one nucleophilic agent, with ionic liquid in a proportion of at least 10 % by weight and optionally with solvents and/or addi-tives allow the formation of a liquid reaction medium with ionic conductivity so that electrolysis can be applied to cause the anodic substitution.
Preferably, the hydrogen atom is directly bound to a carbon atom is part of an alkyl group, more preferably. According to the invention 1, 2 or 3 hydrogen atoms are directly bound to said car-bon atom. Preferably, said carbon atom is a tertiary carbon atom of an alkane or a cycloalkane, an allylic carbon atom of an alkene or a cycloalkene or corresponding diens, a carbon atom in a-position to the arene moiety of an alkylarene, a carbon atom in a-position to the nitrogen atom of an amide, or a carbon atom in a-position to the oxygen atom of an ether.
Preferably, the organic compound according to the invention exhibits an alkyl or alkylen group having at least one hydrogen atom directly bound to a carbon atom.
Particularly preferred or-ganic compounds are (i) alkanes or cycloalkanes having at least one hydrogen atom directly bound to a tertiary carbon atom, (ii) alkenes or cycloalkenes or corresponding dienes having at least one hydrogen atom directly bound to an allylic carbon atom, (iii) alkylarenes having at least one hydrogen atom directly bound to a carbon atom in a-position to the arene moiety, (iv) amides having at least one hydrogen atom directly bound to a carbon atom in a-position to the nitrogen atom, or (v) ethers, esters, carbonates or acetals having at least one hydrogen atom directly bound to a carbon atom in a-position to the oxygen atom.
The organic compound can comprise functional groups that are essentially stable under the reaction conditions. Suitable functional groups comprise carbonyl, thiocarbonyl, ester, thioester, 5 amide, oxycarbonyloxy, urethane, urea, hydroxyl, sulfonyl, sulfinate, sulfonate, sulfate, ether, amine, nitrile, etc. and combinations thereof.
In one embodiment of the present invention, the organic compound provided in step a) is se-lected from compounds of the general formula I
,1 ,2 I-< 1-<
X 0 (I) wherein X is 0, N-R3 or CR4R5, R1 is selected from C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, formyl, C1-C6-alkylcarbonyl and Ci-C6-alkyloxycarbonyl, wherein R1 may also be C1-C6-alkoxy if X is a CR4R5 group, wherein R1 may also be Ci-C6-alkylcarbonyloxy if X is a N-R3 or CR4R5 group, R2 is selected from hydrogen, Ci-C6-alkyl, Ci-C6-alkoxy-Ci-C6-alkyl, C6-Cio-aryl-Ci-C6-alkyl, C3-C12-cycloalkyl and C6-Cio-aryl, R3 is selected from hydrogen, Ci-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, formyl, 01-06-alkylcarbonyl and C1-C6-alkyloxycarbonyl, R4 and R5 are independently selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl and C1-C6-alkoxy, or R1 and R2 together with the X-(C=0)-0 group to which they are bound form a 5- to 7-membered heterocyclic ring, which may contain at least one additional heteroatom or het-eroatom containing group, selected from 0, S, NRc or 0=0, wherein Rc is selected from hydrogen, alkyl, cycloalkyl and aryl, or X is a CR4R5 group and R1 and R4 together with the carbon atom to which they are bound form a 3 to 7 membered carbocyclic ring.
Preferably, X is 0, CH2 or NR3, wherein R3 is 01-04-alkyl or Ci-04-alkylcarbonyl.
In a preferred embodiment, R1 and R2 together with the X-(C=0)-0 group to which they are bound form a 5 to 7 membered heterocyclic ring, which may contain at least one additional het-eroatom or heteroatom containing group, selected from 0, S, NRc or 0=0, wherein Rc is select-ed from hydrogen, alkyl, cycloalkyl or aryl. In this embodiment, X is preferably 0, CH2 or NR3, wherein R3 is 01-04-alkyl or Ci-04-alkylcarbonyl. Further, in this embodiment R1 and R2 together are selected from groups of the formulae -0H2-0H2-, -0H2-0H2-0H2- and -CH(CxH2,0-1)-CH2-, wherein xis 1, 2, 3 or 4.
In a further preferred embodiment, the organic compound provided in step a) is selected from compounds of the general formula la xX
\
A ( R6 H
(la) wherein X is 0, CH2 or NR3, wherein R3 is 01-C4-alkyl or 01-04-alkylcarbonyl, A is an alkylene group selected from -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CHR7-, -CHR7-CH2-, -CH2-CHR7-, -CHR7-CH2-CH2-, -CH2-CHR7-CH2-, and -CH2-CH2-CHR7-, wherein R7is Ci-Cs-alkyl, R6 is hydrogen or 01-C6-alkyl.
Preferably, X is 0 or -CH2-, A is -CH2- or -CHR7-, wherein R7 is 01-04-alkyl, and R6 is hydrogen or Ci-C4-alkyl.
Examples of suitable organic compounds of the general formulas I and la are ethylene car-bonate, propylene carbonate (4-methyl-1,3-dioxolan-2-one) and gamma butyrolactone.
In one embodiment of the present invention, the organic compound provided in step a) is se-lected from compounds of the general formula II
Z-CHR8R9 (II) wherein Z is selected from 06-010-aryl, substituted 06-010-aryl, 01-06-allyl, -NR10R11 group, and 01-06-alkoxy, R8 is selected from hydrogen, 01-06-alkyl, 01-06-alkoxy-01-06-alkyl, wherein R8 may also be 01-06-alkoxy if Z is a 06-C10-aryl or 01-06-allyl, R9 is selected from hydrogen, 01-06-alkyl, 01-06-alkoxy, 01-06-alkoxy-01-06-alkyl, 06-010-aryl, substituted 06-010-aryl, 06-Cio-aryl-C1-06-alkyl, and 03-012-cycloalkyl, or R8 and R9 together form a 04-07-alkylen or a 04-07-alkenylen, and R1 and R" are independently selected from hydrogen, 01-06-alkyl, 06-010-aryl, substituted 06-Cio-aryl, and 01-06-alkylcarbonyl or wherein Z, Wand R9 are independently a 01-06-alkyl.
Preferably, Z is 06-C10-aryl or substituted 06-010-aryl, and R8 and R9 areindependently selected from hydrogen, 01-06-alkyl and 01-06-alkoxy, particularly preferably, Z is 06-C10-aryl or substi-tuted 06-010-aryl, and Wand R9 areindependently selected from hydrogen, 01-04-alkyl and 01-04-alkoxy.
Also preferably, Z is 01-06-alkoxy, R8 is selected from hydrogen and 01-06-alkyl, and R9 is se-lected from hydrogen, 01-06-alkyl, 01-06-alkoxy, 06-010-aryl, and substituted 06-010-aryl, par-ticularly preferably, Z is 01-04-alkoxy, R8 is selected from hydrogen and 01-04-alkyl, and R9 is selected from hydrogen, 01-04-alkyl, 01-04-alkoxy, 06-010-aryl, and substituted 06-010-aryl.
Examples of suitable organic compounds of the general formula II are toluene, benzyl methyl ether and benzaldehyde dimethylacetal.
In the context of the present invention, the expression C1-C6-alkyl comprises straight-chain or branched and saturated or unsaturated C1-C6-alkyl groups. Preferably, the C1-C6-alkyl groups are saturated. Examples of C1-C6-alkyl groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neo-pentyl and n-hexyl.
The above remarks regarding alkyl also apply to the alkyl moiety in alkoxy.
In the context of the present invention, the term "cycloalkyl" denotes a cycloaliphatic radical hav-ing usually from 3 to 12 carbon atoms, preferably 5 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornyl, bicyclo[2.2.2]octyl or ad-amantyl.
In the context of the present invention, the term C6-Cio-aryl refers to mono-or polycyclic aro-matic hydrocarbon radicals. C6-Cio-aryl is preferably phenyl or naphthyl.
In the context of the present invention, the term substituted C6-Cio-aryl refers to mono- or poly-cyclic aromatic hydrocarbon radicals having 1 to 3 aromatic hydrogen atoms, preferably having 1 hydrogen atom substituted. Preferably, the substituents are independently selected from Ci-Cs-alkyl and C1-C6-alkoxy. Preferably, the substituent is in p-position.
Examples of such substit-uents are p-methoxy, p-t-butyl or p-methyl.
In step b) of the process according to the invention, a liquid reaction medium comprising ionic liquid in a proportion of at least 10 % by weight, the organic compound and a nucleophilic agent is provided.
The nucleophilic agent employed in step b) can be any agent or mixtures of agents which pro-vides a nucleophile which is stabile under the electrolysis conditions and which is capable to substitute a hydrogen atom of the organic compound with a nucleophilic group during the anod-ic substitution.
A general formula for the anodic substitution according to the invention is R-H +Nu- 4 R-Nu + H+ + 2 e-, whereas R-H is the organic compound as specified above and Nu- is the nucleophile. Important-ly, the left side of this formula contains two species that would not react with each other where it not for the fact that two electrons are removed from the system.
The nucleophile represented by Nu- is not necessarily negatively charged. A
nucleophile in the context of the invention may also be e.g. pyridine (C5H5N). In such a case a positively charged substitution product is gained.
Nucleophilic agents in the context of the present invention are compounds which possess a nucleophilic group. The nucleophilic group or the nucleophilic agent itself can act as nucleophile in a nucleophilic substitution reaction with the organic compound having at least one hydrogen atom bound to an electrophilic carbon atom. In the course of the nucleophilic substitution reac-tion said hydrogen atom is replaced with the nucleophilic group. In certain cases the nucleo-philic group is identical to the nucleophilic agent (e.g. pyridine (C5H5N)).
In the context of the present invention, the term nucleophile refers to the attacking agent (e.g.
C5H5N, RO- and R000-, but also ROH, RCOOH), whereas the term nucleophilic group refers to the replacement group (e.g. RO- or Rcoa but not ROH or RCOOH).
Preferred nucleophiles of the present invention are selected from the group consisting of HO-, RO-, ROH, R000-, RCOOH, NO2-, NO3-, N3-, OCN-, SCN-,RS03-, SeCN-, ON-, CI-, Br, and I-, whereas R represents an alkyl or arly group, preferably an alkyl group.
Particularly preferred nucleophiles of the present invention are RO- , ROH, R000-, or RCOOH.
Anodic substitutions employing the nucleophiles Ha, Ra, R000-, or NO3- result in the for-mation of 0-0 bonds:
R-H + R'COO-, R-000R' + H+ + 2 e- (anodic acyloxylation) R-H + R'0-, R-OR' + H+ + 2 e- (anodic alkoxylation) R-H + HO-, R-OH + H+ + 2 e- (anodic hydroxylation) R-H + NO3-, R-0NO2+ H+ + 2 e- (anodic nitratation) R-H + R'S03-, R-OSO2R' + H+ + 2 e-Anodic substitutions employing the nucleophiles N3-, OCN-, or NO2- result in the formation of 0-N bonds:
R-H + N3- -> R-N3 + H+ + 2 e- (anodic azidation) R-H + OCN-, R-NCO + H+ + 2 e-R-H + NO2-, R-NO2+ H+ + 2 e- (anodic nitration) Anodic substitution employing the nucleophile ON- results in the formation of a C-C bond:
R-H + ON-, R-ON + H+ + 2 e- (anodic cyanation) Nucleophilic agents in the context of the present invention are compounds which possess a nucleophilic group, e.g. water (with the nucleophilic group HO-), alcohols (e.g. of the formula ROH with the nucleophilic group RO-), carboxylic acids (e.g. of the formula RCOOH with the nucleophilic group R000-), nitrous acid or salts thereof (with the nucleophilic group NO2-), nitric acid or salts thereof (with the nucleophilic group NO3-), hydrazoic acid or salts thereof (with the nucleophilic group N3-), isocyanic acid or salts thereof (with the nucleophilic group OCN-), isothiocyanic acid or salts thereof (with the nucleophilic group SON), sulfonic acid (e.g. of the formula RSO3H with the nucleophilic group R503-), isoselenocyanic acid or salts thereof (with the nucleophilic group SeCN-), hydrogen cyanide or salts thereof (with the nucleophilic group ON-), hydrogen chloride or salts thereof (with the nucleophilic group 01-), hydrogen bromide or salts thereof (with the nucleophilic group Br), or hydrogen iodide or salts thereof (with the nu-cleophilic group I-), whereas R represents an alkyl or arly group, preferably an alkyl group.
Preferred nucleophilic agents of the present invention are alcohols of the formula III
R120H (III) or carboxylic acids of the formula IV
R13000H (IV), where R12 and R13 are 01-012-alkyl or 01-012-perfluorinated alkyl, preferably 01-06-alkyl or Ci-06-perfluorinated alkyl, particular preferably 01-06-alkyl.
In a particular embodiment of the invention, F- is excluded from the nucleophiles. Accordingly, in this particular embodiment, F- providing compounds (fluorinating agents) are excluded from the nucleophilic agents. Also in this particular embodiment, such fluorinating agents are excluded from the ionic liquids.
In the context of the present invention, the expression C1-C6-alkyl comprises straight-chain or branched and saturated or unsaturated C1-C6-alkyl groups. Preferably, the C1-C6-alkyl groups are saturated. Examples of C1-C6-alkyl groups are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neo-pentyl and n-hexyl.
The above remarks regarding alkyl also apply to the alkyl moiety in alkoxy.
In the context of the present invention, the term "cycloalkyl" denotes a cycloaliphatic radical hav-ing usually from 3 to 12 carbon atoms, preferably 5 to 8 carbon atoms, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, norbornyl, bicyclo[2.2.2]octyl or ad-amantyl.
In the context of the present invention, the term C6-Cio-aryl refers to mono-or polycyclic aro-matic hydrocarbon radicals. C6-Cio-aryl is preferably phenyl or naphthyl.
In the context of the present invention, the term substituted C6-Cio-aryl refers to mono- or poly-cyclic aromatic hydrocarbon radicals having 1 to 3 aromatic hydrogen atoms, preferably having 1 hydrogen atom substituted. Preferably, the substituents are independently selected from Ci-Cs-alkyl and C1-C6-alkoxy. Preferably, the substituent is in p-position.
Examples of such substit-uents are p-methoxy, p-t-butyl or p-methyl.
In step b) of the process according to the invention, a liquid reaction medium comprising ionic liquid in a proportion of at least 10 % by weight, the organic compound and a nucleophilic agent is provided.
The nucleophilic agent employed in step b) can be any agent or mixtures of agents which pro-vides a nucleophile which is stabile under the electrolysis conditions and which is capable to substitute a hydrogen atom of the organic compound with a nucleophilic group during the anod-ic substitution.
A general formula for the anodic substitution according to the invention is R-H +Nu- 4 R-Nu + H+ + 2 e-, whereas R-H is the organic compound as specified above and Nu- is the nucleophile. Important-ly, the left side of this formula contains two species that would not react with each other where it not for the fact that two electrons are removed from the system.
The nucleophile represented by Nu- is not necessarily negatively charged. A
nucleophile in the context of the invention may also be e.g. pyridine (C5H5N). In such a case a positively charged substitution product is gained.
Nucleophilic agents in the context of the present invention are compounds which possess a nucleophilic group. The nucleophilic group or the nucleophilic agent itself can act as nucleophile in a nucleophilic substitution reaction with the organic compound having at least one hydrogen atom bound to an electrophilic carbon atom. In the course of the nucleophilic substitution reac-tion said hydrogen atom is replaced with the nucleophilic group. In certain cases the nucleo-philic group is identical to the nucleophilic agent (e.g. pyridine (C5H5N)).
In the context of the present invention, the term nucleophile refers to the attacking agent (e.g.
C5H5N, RO- and R000-, but also ROH, RCOOH), whereas the term nucleophilic group refers to the replacement group (e.g. RO- or Rcoa but not ROH or RCOOH).
Preferred nucleophiles of the present invention are selected from the group consisting of HO-, RO-, ROH, R000-, RCOOH, NO2-, NO3-, N3-, OCN-, SCN-,RS03-, SeCN-, ON-, CI-, Br, and I-, whereas R represents an alkyl or arly group, preferably an alkyl group.
Particularly preferred nucleophiles of the present invention are RO- , ROH, R000-, or RCOOH.
Anodic substitutions employing the nucleophiles Ha, Ra, R000-, or NO3- result in the for-mation of 0-0 bonds:
R-H + R'COO-, R-000R' + H+ + 2 e- (anodic acyloxylation) R-H + R'0-, R-OR' + H+ + 2 e- (anodic alkoxylation) R-H + HO-, R-OH + H+ + 2 e- (anodic hydroxylation) R-H + NO3-, R-0NO2+ H+ + 2 e- (anodic nitratation) R-H + R'S03-, R-OSO2R' + H+ + 2 e-Anodic substitutions employing the nucleophiles N3-, OCN-, or NO2- result in the formation of 0-N bonds:
R-H + N3- -> R-N3 + H+ + 2 e- (anodic azidation) R-H + OCN-, R-NCO + H+ + 2 e-R-H + NO2-, R-NO2+ H+ + 2 e- (anodic nitration) Anodic substitution employing the nucleophile ON- results in the formation of a C-C bond:
R-H + ON-, R-ON + H+ + 2 e- (anodic cyanation) Nucleophilic agents in the context of the present invention are compounds which possess a nucleophilic group, e.g. water (with the nucleophilic group HO-), alcohols (e.g. of the formula ROH with the nucleophilic group RO-), carboxylic acids (e.g. of the formula RCOOH with the nucleophilic group R000-), nitrous acid or salts thereof (with the nucleophilic group NO2-), nitric acid or salts thereof (with the nucleophilic group NO3-), hydrazoic acid or salts thereof (with the nucleophilic group N3-), isocyanic acid or salts thereof (with the nucleophilic group OCN-), isothiocyanic acid or salts thereof (with the nucleophilic group SON), sulfonic acid (e.g. of the formula RSO3H with the nucleophilic group R503-), isoselenocyanic acid or salts thereof (with the nucleophilic group SeCN-), hydrogen cyanide or salts thereof (with the nucleophilic group ON-), hydrogen chloride or salts thereof (with the nucleophilic group 01-), hydrogen bromide or salts thereof (with the nucleophilic group Br), or hydrogen iodide or salts thereof (with the nu-cleophilic group I-), whereas R represents an alkyl or arly group, preferably an alkyl group.
Preferred nucleophilic agents of the present invention are alcohols of the formula III
R120H (III) or carboxylic acids of the formula IV
R13000H (IV), where R12 and R13 are 01-012-alkyl or 01-012-perfluorinated alkyl, preferably 01-06-alkyl or Ci-06-perfluorinated alkyl, particular preferably 01-06-alkyl.
In a particular embodiment of the invention, F- is excluded from the nucleophiles. Accordingly, in this particular embodiment, F- providing compounds (fluorinating agents) are excluded from the nucleophilic agents. Also in this particular embodiment, such fluorinating agents are excluded from the ionic liquids.
The molar ratio of nucleophilic agent (with regard nucleophilic group) to organic compound is preferably in the range from 1:1 to 99:1 (nucleophilic agent: organic compound), more prefera-bly from 2:1 to 99:1.
In a particular embodiment of the invention, the organic compound provided in step a) is select-ed from compounds of the general formula V
Y-CH2R14 (V) wherein Y is selected from C6-Cio-aryl, substituted C6-C10-aryl, C1-C6-allyl, and ¨NR10R11 group, R14 is selected from hydrogen, C1-C6-alkyl, Ci-C6-alkoxy-Ci-C6-alkyl, C6-Cio-aryl-C1-C6-alkyl, C6-C10-aryl, substituted C6-Cio-aryl and C3-C12-cycloalkyl, R10 and R11 arespecified as above, and the nucleophilic agent is an alcohol of the formula III as specified above, whereas in the course of the anodic substitution process two hydrogen atoms are subsequently replaced by ¨0R12 groups resulting in an acetal of the formula VI
Y-C(0R12)2R14 No.
In one embodiment, the invention provides a process of manufacturing an acetal of the general formula VI as specified above by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula V as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound and an alcohol of the general formula III
as specified above;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the gen-eral formula VI, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
Preferably, at least one gas diffusion layer electrode is employed as anode.
An example for such an acetalization process is the conversion of toluene with methanol to benzaldehyde dimethylacetal.
In a particular embodiment of the invention, the organic compound provided in step a) is select-ed from compounds of the general formula V
Y-CH2R14 (V) wherein Y is selected from C6-Cio-aryl, substituted C6-C10-aryl, C1-C6-allyl, and ¨NR1 R11 group, R14 is selected from hydrogen, C1-C6-alkyl, Ci-C6-alkoxy-Ci-C6-alkyl, C6-Cio-aryl-C1-C6-alkyl, C6-Cio-aryl, substituted C6-Cio-aryl and C3-C12-cycloalkyl, R10 and R11 arespecified as above, and the nucleophilic agent is an alcohol of the formula III as specified above, whereas in the course of the anodic substitution process two hydrogen atoms are subsequently replaced by ¨0R12 groups resulting in an acetal of the formula VI
Y-C(0R12)2R14 (VI), and whereas the acetal of formula VI is subsequently hydrolysed resulting in an aldehyde or ketone of formula Via Y-00R14 (Via).
In one embodiment, the invention provides a process of manufacturing an aldehyde or ketone of the general formula Via as specified above by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula V as specified above;
5 b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound and an alcohol of the general formula III
as specified above;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the gen-eral formula VI;
In a particular embodiment of the invention, the organic compound provided in step a) is select-ed from compounds of the general formula V
Y-CH2R14 (V) wherein Y is selected from C6-Cio-aryl, substituted C6-C10-aryl, C1-C6-allyl, and ¨NR10R11 group, R14 is selected from hydrogen, C1-C6-alkyl, Ci-C6-alkoxy-Ci-C6-alkyl, C6-Cio-aryl-C1-C6-alkyl, C6-C10-aryl, substituted C6-Cio-aryl and C3-C12-cycloalkyl, R10 and R11 arespecified as above, and the nucleophilic agent is an alcohol of the formula III as specified above, whereas in the course of the anodic substitution process two hydrogen atoms are subsequently replaced by ¨0R12 groups resulting in an acetal of the formula VI
Y-C(0R12)2R14 No.
In one embodiment, the invention provides a process of manufacturing an acetal of the general formula VI as specified above by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula V as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound and an alcohol of the general formula III
as specified above;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the gen-eral formula VI, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
Preferably, at least one gas diffusion layer electrode is employed as anode.
An example for such an acetalization process is the conversion of toluene with methanol to benzaldehyde dimethylacetal.
In a particular embodiment of the invention, the organic compound provided in step a) is select-ed from compounds of the general formula V
Y-CH2R14 (V) wherein Y is selected from C6-Cio-aryl, substituted C6-C10-aryl, C1-C6-allyl, and ¨NR1 R11 group, R14 is selected from hydrogen, C1-C6-alkyl, Ci-C6-alkoxy-Ci-C6-alkyl, C6-Cio-aryl-C1-C6-alkyl, C6-Cio-aryl, substituted C6-Cio-aryl and C3-C12-cycloalkyl, R10 and R11 arespecified as above, and the nucleophilic agent is an alcohol of the formula III as specified above, whereas in the course of the anodic substitution process two hydrogen atoms are subsequently replaced by ¨0R12 groups resulting in an acetal of the formula VI
Y-C(0R12)2R14 (VI), and whereas the acetal of formula VI is subsequently hydrolysed resulting in an aldehyde or ketone of formula Via Y-00R14 (Via).
In one embodiment, the invention provides a process of manufacturing an aldehyde or ketone of the general formula Via as specified above by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula V as specified above;
5 b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound and an alcohol of the general formula III
as specified above;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the gen-eral formula VI;
10 d) hydrolyzing the acetal of the general formula Vito cause the formation of the aldehyde or ketone of the general formula Via, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
Preferably, at least one gas diffusion layer electrode is employed as anode.
An example for such a manufacturing process is the conversion of toluene with methanol to benzaldehyde dimethylacetal and the subsequent hydrolysis of the benzaldehyde dimethyla-cetal to benzaldehyde. Hydrolysis step can be performed according to protocols known by the skilled person.
In the context of the present invention, the expression "liquid reaction medium" denotes a reac-tion medium that comprises a liquid phase under the reaction conditions of the anodic substitu-tion. This liquid phase contains a sufficient amount of the organic compound to allow anodic substitution. It is not necessary that the liquid phase contains the organic compound in form of a homogeneous solution, as long as a sufficient amount of the organic compound is brought in contact with the electrodes of the electrochemical cell, in particular the anode. Thus, the liquid reaction medium may contain the organic compound in form of a homogeneous solution, colloi-dal solution, molecularly disperse solution, emulsified phase or disperse phase. Finally, it is also possible to introduce a gaseous stream containing the organic compound into the liquid reaction medium.
The liquid reaction medium within the electrochemical oxidation cell comprises ionic liquid in a proportion of at least 10 % by weight based on the total liquid reaction medium, an amount of organic compound solubilized therein, and an amount of nucleophilic agent solubilized therein.
The process according to the invention does not require any additional solvents or additives to establish a anodic substitution reaction with high conversion rates and good selectivity. In par-ticular, the ionic liquid employed also function as conducting salt (electrolyte).
In one embodiment of the present invention, the liquid reaction medium comprises in essence no additional solvents or other additives, i.e. the proportion of solvents and other additives is below 1% by weight, based on the total weight of the liquid reaction medium.
If the liquid reaction medium contains an organic solvent, it is preferably selected from acetoni-trile, ethers, halogenated alkanes, sulfolane and mixtures thereof.
In a specific embodiment of the present invention the liquid reaction medium comprises at least one further additive as redox mediator and/or supportive electrolyte.
Preferably, at least one gas diffusion layer electrode is employed as anode.
An example for such a manufacturing process is the conversion of toluene with methanol to benzaldehyde dimethylacetal and the subsequent hydrolysis of the benzaldehyde dimethyla-cetal to benzaldehyde. Hydrolysis step can be performed according to protocols known by the skilled person.
In the context of the present invention, the expression "liquid reaction medium" denotes a reac-tion medium that comprises a liquid phase under the reaction conditions of the anodic substitu-tion. This liquid phase contains a sufficient amount of the organic compound to allow anodic substitution. It is not necessary that the liquid phase contains the organic compound in form of a homogeneous solution, as long as a sufficient amount of the organic compound is brought in contact with the electrodes of the electrochemical cell, in particular the anode. Thus, the liquid reaction medium may contain the organic compound in form of a homogeneous solution, colloi-dal solution, molecularly disperse solution, emulsified phase or disperse phase. Finally, it is also possible to introduce a gaseous stream containing the organic compound into the liquid reaction medium.
The liquid reaction medium within the electrochemical oxidation cell comprises ionic liquid in a proportion of at least 10 % by weight based on the total liquid reaction medium, an amount of organic compound solubilized therein, and an amount of nucleophilic agent solubilized therein.
The process according to the invention does not require any additional solvents or additives to establish a anodic substitution reaction with high conversion rates and good selectivity. In par-ticular, the ionic liquid employed also function as conducting salt (electrolyte).
In one embodiment of the present invention, the liquid reaction medium comprises in essence no additional solvents or other additives, i.e. the proportion of solvents and other additives is below 1% by weight, based on the total weight of the liquid reaction medium.
If the liquid reaction medium contains an organic solvent, it is preferably selected from acetoni-trile, ethers, halogenated alkanes, sulfolane and mixtures thereof.
In a specific embodiment of the present invention the liquid reaction medium comprises at least one further additive as redox mediator and/or supportive electrolyte.
Redox mediators are used in indirect electrolyses. Typical examples of redox mediators are 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO), triarylamines such as tris(2,4-dibromophenyl)amine or halogenides such as bromide or iodide (Steckhan, Angewandte Chemie 1986, 98,681-699).
In the present invention preferred redox mediators are bromide or iodide salts, particular bro-mide salts such as alkaline bromide salts or tetraalkylammonium bromide salts.
In a specific embodiment of the present invention the liquid reaction medium comprises a bro-mide or iodide salt as further additive. Preferably, in this specific embodiment a GDL electrode is employed as anode and the ionic liquid is employed in a proportion of from 30 to 70 % by weight, preferably from 40 to 50 % by weigh based on the entire liquid reaction medium.
Preferably, in this specific embodiment the organic compound provided in step a) is selected from compounds of the general formula VII
Y-CR152H (VII) wherein Y is specified as above, R15 is a C1-C12-alkoxy, preferably a C1-C6-alkoxy, and the nucleophilic agent is an alcohol of the formula III as specified above, whereas in the course of the anodic substitution process the hydrogen atom is replaced by the ¨0R1 group resulting in an ortho-ester of the formula VIII
Y-CR152(0R12) (VIII).
In one embodiment, the invention provides a process of manufacturing an ortho-ester of the general formula VIII as specified above by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula VII as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound, a bromide or iodide salt, and an alcohol of the general formula III as specified above;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the gen-eral formula VII, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
Preferably, at least one gas diffusion layer electrode is employed as anode.
Such a process of mediated alkoxylation of an acetal to the ortho-ester is improved compared to the mediated alkoxylation processes concerning the current yield reported within the prior art (Grosse Brinkhaus et al., Tetrahedron, 1986, 42, 553-560).
In one embodiment of the invention, the organic compound provided in step a) is a compound of the general formula la as specified above and the nucleophilic agent is a carboxylic acids of the formula (IV) as specified above. Preferably, the nucleophilic acid within this embodiment is a carboxylic acid of the formula IV, wherein R13 is C4-C12-alkyl, preferably Ca-Cs-alkyl having a tertiary carbon atom in alpha position. This process of the invention allows for the anodic substi-tution of an organic compound of formula la such as e.g. ethylene carbonate or propylene car-bonate with a carboxylic acid (acyloxylation) which is very surprisingly related to the easy ring-opening of ethylene carbonate with nucleophiles even if acids are mediocre nucleophiles.
Accordingly, in one embodiment, the invention provides a process of manufacturing an acylox-ylated organic compound of the general formula lb XZo \A4--- IR6 (lb) wherein X, A, and R6 arespecified as above in the context of the general formula la and wherein R13 is C1-C12-alkyl or C1-C12-perfluorinated alkyl, preferably C1-C6-alkyl or 01-06-perfluorinated alkyl, particular preferably Ca-Cs-alkyl having a tertiary carbon atom in a-position by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula la as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound and an carboxylic acid of the general formula IV as specified above;
c) electrolyzing the liquid reaction medium to cause the formation of the acyloxylated or-ganic compound of the general formula lb, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
An overview on the construction possibilities of electrolysis cells that are suitable as electro-chemical oxidation cells for the process of the invention can be found, for example, in Pletcher & Walsh, Industrial Electrochemistry, 2nd Edition, 1990, London, pp. 60ff.
Suitable electrochemical cells for the electrochemical oxidation are undivided cells and divided cells. An undivided cell usually comprises only one electrolyte portion; a divided cell has two or more such portion. The individual electrodes can be connected in parallel (monopolar) or serial-ly (bipolar). In a suitable embodiment, the electrochemical cell employed for the electrochemical oxidation is a monopolar cell comprising a GDL anode and a cathode. In a further suitable em-bodiment, the electrochemical cell employed for the electrochemical oxidation is a cell having bipolar connection of the stacked electrodes.
In a preferred embodiment, the electrochemical oxidation cell is a plate-and-frame cell. Plate-and-frame cells employed in the process of the invention preferably comprise at least one GDL
electrode. This type of cell is composed essentially of usually rectangular electrode plates and frames which surround them. They can be made of polymer material, for example polyethylene, polypropylene, polyvinyl chloride, polyvinylidene fluoride, PTFE, etc. The electrode plate and the associated frame are frequently joined to each other to form an assembly unit. By pressing a plurality of such plate-and-frame units together, a stack which is assembled according to the constructional fashion of filter presses is obtained. Yet further frame units, for example for re-ceiving spacing gauzes, etc. can be inserted in the stack.
The process according to the invention can be performed according to known methods for the anodic substitution by electrolyzing the liquid reaction medium in order to cause replacement of at least a part of the carbon bound hydrogen atoms with nucleophilic groups, with the proviso that the employed liquid reaction medium comprises ionic liquid in a proportion of at least 10 %
by weight.
One or more anodes and one or more cathodes are placed in the liquid reaction medium. Ac-cording to the invention, preferably at least the anode is a GDL electrode. An electric potential (voltage) is established between the anode(s) and cathode(s), resulting in an oxidation reaction (anodic substitution, i.e., replacement of one or more carbon bound hydrogen atoms with car-bon bound nucleophilic groups) at the anode, and a reduction reaction (primarily hydrogen evo-lution) at the cathode.
Preferably, the anodic substitution reaction is performed with a constant current applied; i.e. at a constant voltage and a constant current flow. It is of course also possible, to interrupt the elec-tric current through a current cycle, as described in US 6,267,865.
The current density applied in step c) is in ranges known to the expert.
Preferably, the current density employed in step c) is in a range of from 10 to 250 mA/cm2, more preferably, in the range of from 10 to 100 mA/cm2.
The anodic substitution products can be separated from the reaction medium by customary methods, preferably by distillation. The distillation of the reaction discharge can be carried out by customary methods known to those skilled in the art. Suitable apparatuses for the fractiona-tion by distillation comprise distillation columns such as tray columns, which can be provided with bubble caps, sieve plates, sieve trays, packings, internals, valves, side offtakes, etc. Divid-ing wall columns, which may be provided with side offtakes, recirculations, etc., are especially suitable. A combination of two or more than two distillation columns can be used for the distilla-tion. Further suitable apparatuses are evaporators such as thin film evaporators, falling film evaporators, Sambay evaporators, etc, and combinations thereof.
The use of a liquid reaction medium which comprises ionic liquid in a proportion of at least 10 %
by weight in the process of the invention has a positive effect on at least one of the following parameters: selectivity of the nucleophilic substitution, conversion rate of the nucleophilic substi-tution reaction, current yield, space-time yield, service life of the cell, and accessibility of a broad range of organic compounds for anodic substitution. This positive effect is even more pronounced if additionally a GDL electrode is used as anode. While not being bound to any the-ory it is assumed, that intermediates of the nucleophilic substitution reaction of the organic compound, e.g. cation-radicals generated during the anodic oxidation step, are stabilized by the ionic liquid and that this stabilization is even better if the ionic liquid is used in combination with a GDL anode.
In the present invention preferred redox mediators are bromide or iodide salts, particular bro-mide salts such as alkaline bromide salts or tetraalkylammonium bromide salts.
In a specific embodiment of the present invention the liquid reaction medium comprises a bro-mide or iodide salt as further additive. Preferably, in this specific embodiment a GDL electrode is employed as anode and the ionic liquid is employed in a proportion of from 30 to 70 % by weight, preferably from 40 to 50 % by weigh based on the entire liquid reaction medium.
Preferably, in this specific embodiment the organic compound provided in step a) is selected from compounds of the general formula VII
Y-CR152H (VII) wherein Y is specified as above, R15 is a C1-C12-alkoxy, preferably a C1-C6-alkoxy, and the nucleophilic agent is an alcohol of the formula III as specified above, whereas in the course of the anodic substitution process the hydrogen atom is replaced by the ¨0R1 group resulting in an ortho-ester of the formula VIII
Y-CR152(0R12) (VIII).
In one embodiment, the invention provides a process of manufacturing an ortho-ester of the general formula VIII as specified above by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula VII as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound, a bromide or iodide salt, and an alcohol of the general formula III as specified above;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the gen-eral formula VII, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
Preferably, at least one gas diffusion layer electrode is employed as anode.
Such a process of mediated alkoxylation of an acetal to the ortho-ester is improved compared to the mediated alkoxylation processes concerning the current yield reported within the prior art (Grosse Brinkhaus et al., Tetrahedron, 1986, 42, 553-560).
In one embodiment of the invention, the organic compound provided in step a) is a compound of the general formula la as specified above and the nucleophilic agent is a carboxylic acids of the formula (IV) as specified above. Preferably, the nucleophilic acid within this embodiment is a carboxylic acid of the formula IV, wherein R13 is C4-C12-alkyl, preferably Ca-Cs-alkyl having a tertiary carbon atom in alpha position. This process of the invention allows for the anodic substi-tution of an organic compound of formula la such as e.g. ethylene carbonate or propylene car-bonate with a carboxylic acid (acyloxylation) which is very surprisingly related to the easy ring-opening of ethylene carbonate with nucleophiles even if acids are mediocre nucleophiles.
Accordingly, in one embodiment, the invention provides a process of manufacturing an acylox-ylated organic compound of the general formula lb XZo \A4--- IR6 (lb) wherein X, A, and R6 arespecified as above in the context of the general formula la and wherein R13 is C1-C12-alkyl or C1-C12-perfluorinated alkyl, preferably C1-C6-alkyl or 01-06-perfluorinated alkyl, particular preferably Ca-Cs-alkyl having a tertiary carbon atom in a-position by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula la as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reac-tion medium comprising the organic compound and an carboxylic acid of the general formula IV as specified above;
c) electrolyzing the liquid reaction medium to cause the formation of the acyloxylated or-ganic compound of the general formula lb, characterized in that the liquid reaction medium additionally comprises ionic liquid in a propor-tion of at least 10 % by weight.
An overview on the construction possibilities of electrolysis cells that are suitable as electro-chemical oxidation cells for the process of the invention can be found, for example, in Pletcher & Walsh, Industrial Electrochemistry, 2nd Edition, 1990, London, pp. 60ff.
Suitable electrochemical cells for the electrochemical oxidation are undivided cells and divided cells. An undivided cell usually comprises only one electrolyte portion; a divided cell has two or more such portion. The individual electrodes can be connected in parallel (monopolar) or serial-ly (bipolar). In a suitable embodiment, the electrochemical cell employed for the electrochemical oxidation is a monopolar cell comprising a GDL anode and a cathode. In a further suitable em-bodiment, the electrochemical cell employed for the electrochemical oxidation is a cell having bipolar connection of the stacked electrodes.
In a preferred embodiment, the electrochemical oxidation cell is a plate-and-frame cell. Plate-and-frame cells employed in the process of the invention preferably comprise at least one GDL
electrode. This type of cell is composed essentially of usually rectangular electrode plates and frames which surround them. They can be made of polymer material, for example polyethylene, polypropylene, polyvinyl chloride, polyvinylidene fluoride, PTFE, etc. The electrode plate and the associated frame are frequently joined to each other to form an assembly unit. By pressing a plurality of such plate-and-frame units together, a stack which is assembled according to the constructional fashion of filter presses is obtained. Yet further frame units, for example for re-ceiving spacing gauzes, etc. can be inserted in the stack.
The process according to the invention can be performed according to known methods for the anodic substitution by electrolyzing the liquid reaction medium in order to cause replacement of at least a part of the carbon bound hydrogen atoms with nucleophilic groups, with the proviso that the employed liquid reaction medium comprises ionic liquid in a proportion of at least 10 %
by weight.
One or more anodes and one or more cathodes are placed in the liquid reaction medium. Ac-cording to the invention, preferably at least the anode is a GDL electrode. An electric potential (voltage) is established between the anode(s) and cathode(s), resulting in an oxidation reaction (anodic substitution, i.e., replacement of one or more carbon bound hydrogen atoms with car-bon bound nucleophilic groups) at the anode, and a reduction reaction (primarily hydrogen evo-lution) at the cathode.
Preferably, the anodic substitution reaction is performed with a constant current applied; i.e. at a constant voltage and a constant current flow. It is of course also possible, to interrupt the elec-tric current through a current cycle, as described in US 6,267,865.
The current density applied in step c) is in ranges known to the expert.
Preferably, the current density employed in step c) is in a range of from 10 to 250 mA/cm2, more preferably, in the range of from 10 to 100 mA/cm2.
The anodic substitution products can be separated from the reaction medium by customary methods, preferably by distillation. The distillation of the reaction discharge can be carried out by customary methods known to those skilled in the art. Suitable apparatuses for the fractiona-tion by distillation comprise distillation columns such as tray columns, which can be provided with bubble caps, sieve plates, sieve trays, packings, internals, valves, side offtakes, etc. Divid-ing wall columns, which may be provided with side offtakes, recirculations, etc., are especially suitable. A combination of two or more than two distillation columns can be used for the distilla-tion. Further suitable apparatuses are evaporators such as thin film evaporators, falling film evaporators, Sambay evaporators, etc, and combinations thereof.
The use of a liquid reaction medium which comprises ionic liquid in a proportion of at least 10 %
by weight in the process of the invention has a positive effect on at least one of the following parameters: selectivity of the nucleophilic substitution, conversion rate of the nucleophilic substi-tution reaction, current yield, space-time yield, service life of the cell, and accessibility of a broad range of organic compounds for anodic substitution. This positive effect is even more pronounced if additionally a GDL electrode is used as anode. While not being bound to any the-ory it is assumed, that intermediates of the nucleophilic substitution reaction of the organic compound, e.g. cation-radicals generated during the anodic oxidation step, are stabilized by the ionic liquid and that this stabilization is even better if the ionic liquid is used in combination with a GDL anode.
Examples The following examples are intended for further illustration of the present invention.
Example 1 for comparison In a 100 ml undivided electrolysis cell 6.5 g toluene, 34.1 g methanol and 2.6 g methyltribu-tylammonium methylsulfate (MTBS, 6 % by weight) as supporting electrolyte were electrolyzed for 7 F using a graphite anode (10 cm2) and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 65 % conversion of toluene, a selec-tivity to benzaldehyde dimethylacetal of 7 % and a current yield of 2 %. The results of this ex-periment are summarized in table 1.
Example 2 In a 100 ml undivided electrolysis cell 7.5 g toluene, 17.0 g methanol and 25.5 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed for 7 F using a graphite anode (10 cm2) and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 88 % conversion of toluene, a selec-tivity to benzaldehyde dimethylacetal of 32 % and a current yield of 15 %. The results of this experiment are summarized in table 1.
Example 3 In a 100 ml undivided electrolysis cell 13.1 g toluene, 29.5 g methanol and 9.8 g methyltribu-tylammonium methylsulfate (MTBS, 12% by weight) as supporting electrolyte were electrolyzed for 7 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 34 mA/cm2. The GC analysis showed 87 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 22 % and a current yield of 9 %. The GDL electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 4 In a 100 ml undivided electrolysis cell 13.1 g toluene, 29.5 g methanol and 9.8 g methyltribu-tylammonium methylsulfate (MTBS, 25 % by weight) as supporting electrolyte were electrolyzed for 7 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 34 mA/cm2. The GC analysis showed 89 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 29 % and a current yield of 13 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 5 In a 100 ml undivided electrolysis cell 13.1 g toluene, 29.5 g methanol and 9.8 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed 10 for 8 F using a commercial GDL (H2315 IX11CX45 from Freudenberg, 10 cm2) as anode and a stainless steel cathode (10 cm2). The current density was 34 mA/cm2. The GC
analysis showed 98 % conversion of toluene, a selectivity to benzaldehyde dimethylacetal of 45 % and a current yield of 21 %. The results of this experiment are summarized in table 1.
Example 6 In a 100 ml undivided electrolysis cell 7.9 g toluene, 17.9 g methanol and 26.9 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed for 7 F using a commercial GDL (Sigracet GDL 25 BC from SGL Group, 10 cm2) as anode and a stainless steel cathode (10 cm2). The current density was 34 mA/cm2. The GC
analysis showed 96 % conversion of toluene, a selectivity to benzaldehyde dimethylacetal of 45 % and a current yield of 23 %. The results of this experiment are summarized in table 1.
Example 7 In a 100 ml undivided electrolysis cell 7.6 g toluene, 17.2 g methanol and 25.8 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 34 mA/cm2. The GC analysis showed 97 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 48 % and a current yield of 25 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 8 In a 100 ml undivided electrolysis cell 8.1 g toluene, 18.3 g methanol and 27.4 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 65 mA/cm2. The GC analysis showed 94 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 49 % and a current yield of 27 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 9 In a 100 ml undivided electrolysis cell 4.9 g toluene, 10.9 g methanol and 36.8 g methyltribu-tylammonium methylsulfate (MTBS, 70 % by weight) as supporting electrolyte were electrolyzed for 6 F using a graphite anode (10 cm2) and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 81 % conversion of toluene, a selec-tivity to benzaldehyde dimethylacetal of 30 % and a current yield of 15 %. The results of this experiment are summarized in table 1.
Example 10 In a 100 ml undivided electrolysis cell 5.2 g toluene, 11.7 g methanol and 39.4 g methyltribu-tylammonium methylsulfate (MTBS, 70 % by weight) as supporting electrolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 34 mA/cm2. The GC analysis showed 93 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 50 % and a current yield of 28 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 11 In a 100 ml undivided electrolysis cell 5.9 g toluene, 13.2 g methanol and 44,4 g 1-Ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (EMimid-TFSI, 70 % by weight) as support-ing electrolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 98%
conversion of toluene, a selectivity to benzaldehyde dimethylacetal of 50 %
and a current yield of 30 %. The GDL electrode has been be manufactured according to US 6,103,077 using car-bon black. The results of this experiment are summarized in table 1.
Example 12 In a 100 ml undivided electrolysis cell 5.6 g toluene, 12.7 g methanol and 42.8 g methyltribu-tylammonium bis(trifluoromethylsulfonyl)imide (MTB-TFSI, 70 % by weight) as supporting elec-trolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 98 % conver-sion of toluene, a selectivity to benzaldehyde dimethylacetal of 50 % and a current yield of 32 %. The GDL electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 13 In a 100 ml undivided electrolysis cell 6.0 g toluene, 13.5 g methanol and 45.4 g methyltribu-tylammonium bis(trifluoromethylsulfonyl)imide (MTB-TFSI, 70 % by weight) as supporting elec-trolyte were electrolyzed for 5.5 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 60 mA/cm2. The GC analysis showed 95 % conver-sion of toluene, a selectivity to benzaldehyde dimethylacetal of 54 % and a current yield of 35 %. The GDL electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Table 1: Acetalization of toluene Exam- Anode % IL electro- F c. d. cony. Select. c.
y.
pie lyte [mA/cm2] [%] IN IN
1 Graphite 6 MTBS 7 34 65 7 2 2 Graphite 51 MTBS 7 34 88 32 15 Commercial GDL
Commercial 9 Graphite 70 MTBS 6 34 81 30 15 EMimid-5.
Example 14 for comparison In a 100 ml undivided electrolysis cell 6.7 g benzaldehyde dimethylacetal and 37.6 g methanol and 0.45 g sodium bromide (1 % by weight) as mediator /supporting electrolyte were electro-lyzed for 2.5 F using graphite(10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 18 % conversion of benzal-dehyde dimethylacetal, a selectivity to benzoic acid ortho-ester of 49 % and a current yield of 7 %.
Example 15 for comparison In a 100 ml undivided electrolysis cell 6.1 g benzaldehyde dimethylacetal and 33.9 g methanol and 0.82 g tetrabutyl ammonium bromide (2 % by weight) as mediator /supporting electrolyte were electrolyzed for 2.5 F using graphite(10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 24 %
conversion of benzaldehyde dimethylacetal, a selectivity to benzoic acid ortho-ester of 59 %
and a current yield of 11 %.
Example 16 In a 100 ml undivided electrolysis cell 5.2 g benzaldehyde dimethylacetal, 21.2 g methanol, and 23.1 g methyltributylammonium methylsulfate (MTBS, 45 % by weight) and 2.2 g tetrabutyl ammonium bromide (4 % by weight) as mediator were electrolyzed for 5 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 72 % conversion of benzaldehyde dimethylacetal, a selectivi-ty to benzoic acid ortho-ester of 68 % and a current yield of 20 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black.
Example 17 In a 100 ml undivided electrolysis cell 4.9 g benzaldehyde dimethylacetal, 20.2 g methanol, and 21.8 g methyltributylammonium methylsulfate (MTBS, 42 % by weight) and 5.1 g tetrabutyl ammonium bromide (10 % by weight) as mediator were electrolyzed for 5 F using a GDL
(10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 31 % conversion of benzaldehyde dimethylacetal, a selectivi-ty to benzoic acid ortho-ester of 83 % and a current yield of 10 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black.
Example 18 In a 100 ml undivided electrolysis cell 5.6 g ethylene carbonate, 27 g pivalic acid and 22.3 g 5 tetraoctylammonium bis(trifluoromethylsulfonyl)imide (41 % by weight) as supporting electrolyte were electrolyzed for 4.7 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 10 mA/cm2. The NMR and GC analysis showed 67%
conversion of ethylene carbonate, the yield is 18 % of 4-(tert-butyl) carbonyloxy-1,3-dioxolan-2-one. The GDL electrode has been be manufactured according to US 6,103,077 using carbon 10 black.
Example 1 for comparison In a 100 ml undivided electrolysis cell 6.5 g toluene, 34.1 g methanol and 2.6 g methyltribu-tylammonium methylsulfate (MTBS, 6 % by weight) as supporting electrolyte were electrolyzed for 7 F using a graphite anode (10 cm2) and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 65 % conversion of toluene, a selec-tivity to benzaldehyde dimethylacetal of 7 % and a current yield of 2 %. The results of this ex-periment are summarized in table 1.
Example 2 In a 100 ml undivided electrolysis cell 7.5 g toluene, 17.0 g methanol and 25.5 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed for 7 F using a graphite anode (10 cm2) and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 88 % conversion of toluene, a selec-tivity to benzaldehyde dimethylacetal of 32 % and a current yield of 15 %. The results of this experiment are summarized in table 1.
Example 3 In a 100 ml undivided electrolysis cell 13.1 g toluene, 29.5 g methanol and 9.8 g methyltribu-tylammonium methylsulfate (MTBS, 12% by weight) as supporting electrolyte were electrolyzed for 7 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 34 mA/cm2. The GC analysis showed 87 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 22 % and a current yield of 9 %. The GDL electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 4 In a 100 ml undivided electrolysis cell 13.1 g toluene, 29.5 g methanol and 9.8 g methyltribu-tylammonium methylsulfate (MTBS, 25 % by weight) as supporting electrolyte were electrolyzed for 7 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 34 mA/cm2. The GC analysis showed 89 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 29 % and a current yield of 13 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 5 In a 100 ml undivided electrolysis cell 13.1 g toluene, 29.5 g methanol and 9.8 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed 10 for 8 F using a commercial GDL (H2315 IX11CX45 from Freudenberg, 10 cm2) as anode and a stainless steel cathode (10 cm2). The current density was 34 mA/cm2. The GC
analysis showed 98 % conversion of toluene, a selectivity to benzaldehyde dimethylacetal of 45 % and a current yield of 21 %. The results of this experiment are summarized in table 1.
Example 6 In a 100 ml undivided electrolysis cell 7.9 g toluene, 17.9 g methanol and 26.9 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed for 7 F using a commercial GDL (Sigracet GDL 25 BC from SGL Group, 10 cm2) as anode and a stainless steel cathode (10 cm2). The current density was 34 mA/cm2. The GC
analysis showed 96 % conversion of toluene, a selectivity to benzaldehyde dimethylacetal of 45 % and a current yield of 23 %. The results of this experiment are summarized in table 1.
Example 7 In a 100 ml undivided electrolysis cell 7.6 g toluene, 17.2 g methanol and 25.8 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 34 mA/cm2. The GC analysis showed 97 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 48 % and a current yield of 25 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 8 In a 100 ml undivided electrolysis cell 8.1 g toluene, 18.3 g methanol and 27.4 g methyltribu-tylammonium methylsulfate (MTBS, 51 % by weight) as supporting electrolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 65 mA/cm2. The GC analysis showed 94 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 49 % and a current yield of 27 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 9 In a 100 ml undivided electrolysis cell 4.9 g toluene, 10.9 g methanol and 36.8 g methyltribu-tylammonium methylsulfate (MTBS, 70 % by weight) as supporting electrolyte were electrolyzed for 6 F using a graphite anode (10 cm2) and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 81 % conversion of toluene, a selec-tivity to benzaldehyde dimethylacetal of 30 % and a current yield of 15 %. The results of this experiment are summarized in table 1.
Example 10 In a 100 ml undivided electrolysis cell 5.2 g toluene, 11.7 g methanol and 39.4 g methyltribu-tylammonium methylsulfate (MTBS, 70 % by weight) as supporting electrolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2).
The current den-sity was 34 mA/cm2. The GC analysis showed 93 % conversion of toluene, a selectivity to ben-zaldehyde dimethylacetal of 50 % and a current yield of 28 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 11 In a 100 ml undivided electrolysis cell 5.9 g toluene, 13.2 g methanol and 44,4 g 1-Ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide (EMimid-TFSI, 70 % by weight) as support-ing electrolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 98%
conversion of toluene, a selectivity to benzaldehyde dimethylacetal of 50 %
and a current yield of 30 %. The GDL electrode has been be manufactured according to US 6,103,077 using car-bon black. The results of this experiment are summarized in table 1.
Example 12 In a 100 ml undivided electrolysis cell 5.6 g toluene, 12.7 g methanol and 42.8 g methyltribu-tylammonium bis(trifluoromethylsulfonyl)imide (MTB-TFSI, 70 % by weight) as supporting elec-trolyte were electrolyzed for 6 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 98 % conver-sion of toluene, a selectivity to benzaldehyde dimethylacetal of 50 % and a current yield of 32 %. The GDL electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Example 13 In a 100 ml undivided electrolysis cell 6.0 g toluene, 13.5 g methanol and 45.4 g methyltribu-tylammonium bis(trifluoromethylsulfonyl)imide (MTB-TFSI, 70 % by weight) as supporting elec-trolyte were electrolyzed for 5.5 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 60 mA/cm2. The GC analysis showed 95 % conver-sion of toluene, a selectivity to benzaldehyde dimethylacetal of 54 % and a current yield of 35 %. The GDL electrode has been be manufactured according to US 6,103,077 using carbon black. The results of this experiment are summarized in table 1.
Table 1: Acetalization of toluene Exam- Anode % IL electro- F c. d. cony. Select. c.
y.
pie lyte [mA/cm2] [%] IN IN
1 Graphite 6 MTBS 7 34 65 7 2 2 Graphite 51 MTBS 7 34 88 32 15 Commercial GDL
Commercial 9 Graphite 70 MTBS 6 34 81 30 15 EMimid-5.
Example 14 for comparison In a 100 ml undivided electrolysis cell 6.7 g benzaldehyde dimethylacetal and 37.6 g methanol and 0.45 g sodium bromide (1 % by weight) as mediator /supporting electrolyte were electro-lyzed for 2.5 F using graphite(10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 18 % conversion of benzal-dehyde dimethylacetal, a selectivity to benzoic acid ortho-ester of 49 % and a current yield of 7 %.
Example 15 for comparison In a 100 ml undivided electrolysis cell 6.1 g benzaldehyde dimethylacetal and 33.9 g methanol and 0.82 g tetrabutyl ammonium bromide (2 % by weight) as mediator /supporting electrolyte were electrolyzed for 2.5 F using graphite(10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 24 %
conversion of benzaldehyde dimethylacetal, a selectivity to benzoic acid ortho-ester of 59 %
and a current yield of 11 %.
Example 16 In a 100 ml undivided electrolysis cell 5.2 g benzaldehyde dimethylacetal, 21.2 g methanol, and 23.1 g methyltributylammonium methylsulfate (MTBS, 45 % by weight) and 2.2 g tetrabutyl ammonium bromide (4 % by weight) as mediator were electrolyzed for 5 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 72 % conversion of benzaldehyde dimethylacetal, a selectivi-ty to benzoic acid ortho-ester of 68 % and a current yield of 20 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black.
Example 17 In a 100 ml undivided electrolysis cell 4.9 g benzaldehyde dimethylacetal, 20.2 g methanol, and 21.8 g methyltributylammonium methylsulfate (MTBS, 42 % by weight) and 5.1 g tetrabutyl ammonium bromide (10 % by weight) as mediator were electrolyzed for 5 F using a GDL
(10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 34 mA/cm2. The GC analysis showed 31 % conversion of benzaldehyde dimethylacetal, a selectivi-ty to benzoic acid ortho-ester of 83 % and a current yield of 10 %. The GDL
electrode has been be manufactured according to US 6,103,077 using carbon black.
Example 18 In a 100 ml undivided electrolysis cell 5.6 g ethylene carbonate, 27 g pivalic acid and 22.3 g 5 tetraoctylammonium bis(trifluoromethylsulfonyl)imide (41 % by weight) as supporting electrolyte were electrolyzed for 4.7 F using a GDL (10 cm2) as anode and a stainless steel cathode (10 cm2). The applied current density was 10 mA/cm2. The NMR and GC analysis showed 67%
conversion of ethylene carbonate, the yield is 18 % of 4-(tert-butyl) carbonyloxy-1,3-dioxolan-2-one. The GDL electrode has been be manufactured according to US 6,103,077 using carbon 10 black.
Claims (19)
1. A process of anodic substitution comprising the steps of:
a) providing an organic compound comprising at least one hydrogen atom bound to a carbon atom;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound and a nucleophilic agent;
c) electrolyzing the liquid reaction medium to cause replacement of at least a part of said hydrogen atoms with the nucleophilic group of the nucleophilic agent, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
a) providing an organic compound comprising at least one hydrogen atom bound to a carbon atom;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound and a nucleophilic agent;
c) electrolyzing the liquid reaction medium to cause replacement of at least a part of said hydrogen atoms with the nucleophilic group of the nucleophilic agent, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
2. The process of claim 1, whereas the anode is a gas diffusion layer electrode.
3. The process of claim 2, whereas the gas diffusion layer electrode contains a substrate and a microporous layer containing carbon particles as main component.
4. The process of claim 2, whereas the gas diffusion layer electrode contains a substrate and a microporous layer containing carbon black as main component.
5. The process of any of the claims from 1 to 4, whereas the ionic liquid is having an organ-ic cation which comprises an ammonium group.
6. The process of any of the claims from 1 to 5, whereas the organic compound is selected of the group consisting of (i) alkanes or cycloalkanes having at least one hydrogen atom directly bound to a tertiary carbon atom, (ii) alkenes or cycloalkenes or corresponding dienes having at least one hydrogen atom directly bound to an allylic carbon atom, (iii) alkylarenes having at least one hydrogen atom directly bound to a carbon atom in .alpha.-position to the arene moiety, (iv) amides having at least one hydrogen atom directly bound to a carbon atom in .alpha.-position to the nitrogen atom, or (v) ethers, esters, car-bonates or acetals having at least one hydrogen atom directly bound to a carbon atom in .alpha.-position to the oxygen atom.
7. The process of any of the claims from 1 to 5, whereas the organic compound is a com-pound of formula l wherein X is O, N-R3 or CR4R5, R1 is selected from C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, formyl, C1-C6-alkylcarbonyl and C1-C6-alkyloxycarbonyl, wherein R1 may also be C1-C6-alkoxy if X is a CR4R5 group, wherein R1 may also be C1-C6-alkylcarbonyloxy if X is a N-R3 or CR4R5 group, R2 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, C6-C10-aryl-C1-C6-alkyl, C3-C12-cycloalkyl and C6-C10-aryl, R3 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, formyl, C1-C6-alkylcarbonyl and C1-C6-alkyloxycarbonyl, R4 and R5 are independently selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-alkyl and C1-C6-alkoxy, or R1 and R2 together with the X-(C=O)-O group to which they are bound form a 5- to 7-membered heterocyclic ring, which may contain at least one additional heteroa-tom or heteroatom containing group, selected from O, S, NRC or C=O, wherein R
c is selected from hydrogen, alkyl, cycloalkyl and aryl, or X is a CR4R5 group and R1 and R4 together with the carbon atom to which they are bound form a 3 to 7 membered carbocyclic ring.
c is selected from hydrogen, alkyl, cycloalkyl and aryl, or X is a CR4R5 group and R1 and R4 together with the carbon atom to which they are bound form a 3 to 7 membered carbocyclic ring.
8. The process of any of the claims from 1 to 5, whereas the organic compound is a com-pound of formula I
wherein X is 0, CH2 or NR3, wherein R3 is C1-C4-alkyl or C1-C4-alkylcarbonyl, A is an alkylene group selected from -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CHR7-, -CHR7-CH2-, -CH2-CHR7-, -CHR7-CH2-CH2-, -CH2-CHR7-CH2-, and -CH2-CH2-C H R7-, wherein R7 is C1-C6-alkyl, R6 is hydrogen or C1-C6-alkyl.
wherein X is 0, CH2 or NR3, wherein R3 is C1-C4-alkyl or C1-C4-alkylcarbonyl, A is an alkylene group selected from -CH2-, -CH2-CH2-, -CH2-CH2-CH2-, -CHR7-, -CHR7-CH2-, -CH2-CHR7-, -CHR7-CH2-CH2-, -CH2-CHR7-CH2-, and -CH2-CH2-C H R7-, wherein R7 is C1-C6-alkyl, R6 is hydrogen or C1-C6-alkyl.
9. The process of any of the claims from 1 to 5, whereas the organic compound is a com-pound of formula II
Z-CHR8R9 (II) wherein Z is selected from C6-C10-aryl, substituted C6-C10-aryl, C1-C6-allyl, -NR10R1 1 group , and C1-C6-alkoxy, R8 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, wherein R8 may also be C1-C6-alkoxy if Z is a C6-C10-aryl or C1-C6-allyl, R9 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy, C1-C6-alkoxy-C1-C6-alkyl, C6-C10-aryl, substituted C6-C10-aryl, C6-C10-aryl-C1-C6-alkyl, and C3-C12-cycloalkyl, or R8 and R9 together form a C4-C7-alkylen or a C4-C7-alkenylen, and R10 and R11 are independently selected from hydrogen, C1-C6-alkyl, C6-C10-aryl, substi-tuted C6-C10-aryl, and C1-C6-alkylcarbonyl or wherein Z, R8 and R9 are independently a C1-C6-alkyl.
Z-CHR8R9 (II) wherein Z is selected from C6-C10-aryl, substituted C6-C10-aryl, C1-C6-allyl, -NR10R1 1 group , and C1-C6-alkoxy, R8 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, wherein R8 may also be C1-C6-alkoxy if Z is a C6-C10-aryl or C1-C6-allyl, R9 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy, C1-C6-alkoxy-C1-C6-alkyl, C6-C10-aryl, substituted C6-C10-aryl, C6-C10-aryl-C1-C6-alkyl, and C3-C12-cycloalkyl, or R8 and R9 together form a C4-C7-alkylen or a C4-C7-alkenylen, and R10 and R11 are independently selected from hydrogen, C1-C6-alkyl, C6-C10-aryl, substi-tuted C6-C10-aryl, and C1-C6-alkylcarbonyl or wherein Z, R8 and R9 are independently a C1-C6-alkyl.
10. The process of any of the claims from 1 to 9, whereas the nucleophilic agent is selected from a group consisting of water, alcohols, carboxylic acids, nitrous acid or salts thereof, nitric acid or salts thereof, hydrozoic acid or salts thereof, isocyanic acid or salts thereof, isothiocyanic acid or salts thereof, sulfonic acid, isoselenocyanic acid or salts thereof, hydrogen cyanide or salts thereof, hydrogen chloride or salts thereof, hydrogen bromide or salts thereof, and hydrogen iodide or salts thereof.
11. The process of any of the claims from 1 to 9, whereas the nucleophilic agent is selected from a group consisting of alcohols of the formula III
R12OH (III) or carboxylic acids of the formula IV
R13COOH (IV), where R12 and R13 are C1-C12-alkyl or C1-C12-perfluorinated alkyl.
R12OH (III) or carboxylic acids of the formula IV
R13COOH (IV), where R12 and R13 are C1-C12-alkyl or C1-C12-perfluorinated alkyl.
12. The process of any of the claims from 1 to 9, whereas fluorinating agents are excluded from as nucleophilic agent.
13. The process of any of the claims from 1 to 12, whereas the liquid reaction medium addi-tionally comprises an additive selected from the group consisting of bromide salts and iodide salts.
14. The process of any of the claims from 1 to 13, whereas the electrochemical cell is an undivided cell.
15. The process of any of the claims from 1 to 14, whereas the cathode is selected from the group consisting of Pt, Pb, Ni, graphite, felt materials like coal or graphite felts, stainless steel and GDL electrodes.
16. A process of manufacturing an acetal of the general formula VI
Y-C(OR12)2R14 (VI) starting from an organic compound of the general formula V
Y-CH2R14 (V) wherein Y is selected from C6-C10-aryl, substituted C6-C10-aryl, C1-C6-allyl, and ¨NR10R11 group , R12 is C1-C12-alkyl or C1-C12-per-fluorinated alkyl R14 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, C6-C10-aryl-C1-C6-alkyl, C6-C10-aryl, substituted C6-C10-aryl and C3-C12-cycloalkyl, R10 and R11 are independently selected from hydrogen, C1-C6-alkyl, C6-C10-aryl, substi-tuted C6-C10-aryl, and C1-C6-alkylcarbonyl by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula V as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound and an alcohol of the general formula III as specified in claim 11;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the general formula VI, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
Y-C(OR12)2R14 (VI) starting from an organic compound of the general formula V
Y-CH2R14 (V) wherein Y is selected from C6-C10-aryl, substituted C6-C10-aryl, C1-C6-allyl, and ¨NR10R11 group , R12 is C1-C12-alkyl or C1-C12-per-fluorinated alkyl R14 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, C6-C10-aryl-C1-C6-alkyl, C6-C10-aryl, substituted C6-C10-aryl and C3-C12-cycloalkyl, R10 and R11 are independently selected from hydrogen, C1-C6-alkyl, C6-C10-aryl, substi-tuted C6-C10-aryl, and C1-C6-alkylcarbonyl by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula V as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound and an alcohol of the general formula III as specified in claim 11;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the general formula VI, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
17. A process of manufacturing an aldehyde or ketone of the general formula Vla Y-COR14 (Vla) starting from an organic compound of the general formula V
Y-CH2R14 (V) wherein Y is selected from C6-C10-aryl, substituted C6-C10-aryl, C1-C6-allyl, and ¨NR10R11 group , R12 is C1-C12-alkyl or C1-C12-perfluorinated alkyl R14 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, C6-C10-aryl-C1-C6-alkyl, C6-C10-aryl, substituted C6-C10-aryl and C3-C12-cycloalkyl, R10 and R11 are independently selected from hydrogen, C1-C6-alkyl, C6-C10-aryl, substi-tuted C6-C10-aryl, and C1-C6-alkylcarbonyl by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula V as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound and an alcohol of the general formula III as specified in claim 11;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the general formula VI;
d) hydrolyzing the acetal of the general formula VI to cause the formation of the al-dehyde or ketone of the general formula Vla, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
Y-CH2R14 (V) wherein Y is selected from C6-C10-aryl, substituted C6-C10-aryl, C1-C6-allyl, and ¨NR10R11 group , R12 is C1-C12-alkyl or C1-C12-perfluorinated alkyl R14 is selected from hydrogen, C1-C6-alkyl, C1-C6-alkoxy-C1-C6-alkyl, C6-C10-aryl-C1-C6-alkyl, C6-C10-aryl, substituted C6-C10-aryl and C3-C12-cycloalkyl, R10 and R11 are independently selected from hydrogen, C1-C6-alkyl, C6-C10-aryl, substi-tuted C6-C10-aryl, and C1-C6-alkylcarbonyl by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula V as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound and an alcohol of the general formula III as specified in claim 11;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the general formula VI;
d) hydrolyzing the acetal of the general formula VI to cause the formation of the al-dehyde or ketone of the general formula Vla, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
18. A process of manufacturing an ortho-ester of the formula VIII
Y-CR15 2(OR12) (VIII) starting from an organic compound of the general formula VII
Y-CR15 2H (VII) wherein Y is specified as above , R12 is C1-C12-alkyl or C1-C12-perfluorinated alkyl R15 is a C1-C12-alkoxyõ
by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula VII as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound, a bromide or iodide salt, and an alcohol of the general formula III as specified in claim 11;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the general formula VII, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
Y-CR15 2(OR12) (VIII) starting from an organic compound of the general formula VII
Y-CR15 2H (VII) wherein Y is specified as above , R12 is C1-C12-alkyl or C1-C12-perfluorinated alkyl R15 is a C1-C12-alkoxyõ
by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula VII as specified above;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound, a bromide or iodide salt, and an alcohol of the general formula III as specified in claim 11;
c) electrolyzing the liquid reaction medium to cause the formation of the acetal of the general formula VII, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
19. A process of manufacturing an acyloxylated organic compound of the formula lb starting from an organic compound of the general formula la as specified in claim 8 wherein X, A, and R6 are as specified in claim 8 in the context of the general formula la and R13 is C1-C12-alkyl or C1-C12-perfluorinated alkyl, by anodic substitution comprising the steps of:
a) providing an organic compound of the general formula la as specified in claim 8;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound and an carboxylic acid of the general formula IV as specified in claim 11;
c) electrolyzing the liquid reaction medium to cause the formation of the acyloxylat-ed organic compound of the general formula lb, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
a) providing an organic compound of the general formula la as specified in claim 8;
b) providing, in an electrochemical cell comprising a cathode and an anode, a liquid reaction medium comprising the organic compound and an carboxylic acid of the general formula IV as specified in claim 11;
c) electrolyzing the liquid reaction medium to cause the formation of the acyloxylat-ed organic compound of the general formula lb, characterized in that the liquid reaction medium additionally comprises ionic liquid in a proportion of at least 10 % by weight.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP12172250 | 2012-06-15 | ||
| EP12172250.8 | 2012-06-15 | ||
| PCT/EP2013/061555 WO2013186094A2 (en) | 2012-06-15 | 2013-06-05 | Anodic oxidation of organic substrates in the presence of nucleophiles |
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| Publication Number | Publication Date |
|---|---|
| CA2876566A1 true CA2876566A1 (en) | 2013-12-19 |
Family
ID=48628629
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| CA2876566A Abandoned CA2876566A1 (en) | 2012-06-15 | 2013-06-05 | Anodic oxidation of organic substrates in the presence of nucleophiles |
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| EP (1) | EP2861785A2 (en) |
| JP (1) | JP2015527483A (en) |
| KR (1) | KR20150023709A (en) |
| CN (1) | CN104379814A (en) |
| CA (1) | CA2876566A1 (en) |
| TW (1) | TW201400469A (en) |
| WO (1) | WO2013186094A2 (en) |
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| EP3321250A1 (en) * | 2016-11-15 | 2018-05-16 | Covestro Deutschland AG | Electrochemical method for the production of arylalkylcarbonates and diaryl carbonates |
| WO2019016903A1 (en) * | 2017-07-19 | 2019-01-24 | 宇部興産株式会社 | Nonaqueous electrolytic solution and electricity storage device using same |
| CN109321940A (en) * | 2018-11-30 | 2019-02-12 | 西南大学 | A kind of the electrochemical oxidation synthetic method and its application of amide |
| CN109930171B (en) * | 2019-04-12 | 2020-01-17 | 天津理工大学 | Green and efficient acetal synthesis method |
| CN111394747B (en) * | 2020-04-10 | 2021-03-30 | 浙江工业大学 | Green electrochemical synthesis method of 2-acyloxy aniline derivatives |
| CN113046772B (en) * | 2021-03-18 | 2022-03-04 | 南华大学 | Electrochemical synthesis method of 4-selenopyrazole derivative |
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| DE2848397C2 (en) | 1978-11-08 | 1982-09-23 | Basf Ag, 6700 Ludwigshafen | Electrochemical production of benzaldehyde dialkyl acetals substituted in the 4-position |
| DE3048992A1 (en) * | 1980-12-24 | 1982-07-15 | Hoechst Ag, 6000 Frankfurt | 4,4'-DIPHENYL ETHER-DIALDEHYDE-BIS-DIMETHYL ACETAL AND A METHOD FOR THE PRODUCTION THEREOF |
| DE3142626A1 (en) * | 1981-10-28 | 1983-05-05 | Basf Ag, 6700 Ludwigshafen | ELECTROCHEMICAL METHOD FOR PRODUCING 2,5-DIALKOXY-2,5-DIHYDROFURANES |
| EP0241432B1 (en) | 1986-03-07 | 1993-08-11 | Tanaka Kikinzoku Kogyo K.K. | Gas permeable electrode |
| US4748095A (en) | 1987-03-06 | 1988-05-31 | Nagakazu Furuya | Halogen cell |
| DE3820895A1 (en) * | 1988-06-21 | 1989-12-28 | Basf Ag | PYRETHROIDS, METHOD FOR THEIR PRODUCTION AND THEIR USE FOR CONTROLLING PESTIES |
| US5618392A (en) | 1991-10-31 | 1997-04-08 | Tanaka Kikinzoku Kogyo K.K. | Gas diffusion electrode |
| US5443698A (en) * | 1994-05-06 | 1995-08-22 | Huls America Inc. | Electrosynthesis of metal carboxylates |
| DE19618854A1 (en) * | 1996-05-10 | 1997-11-13 | Basf Ag | Process for the production of phthalides |
| WO1998000580A1 (en) * | 1996-06-28 | 1998-01-08 | E.I. Du Pont De Nemours And Company | In-situ halogenation of compounds in an electrochemical cell |
| US6267865B1 (en) | 1997-05-02 | 2001-07-31 | 3M Innovative Properties Company | Electrochemical fluorination using interrupted current |
| US6103077A (en) | 1998-01-02 | 2000-08-15 | De Nora S.P.A. | Structures and methods of manufacture for gas diffusion electrodes and electrode components |
| DE19944989A1 (en) * | 1999-09-20 | 2001-03-22 | Basf Ag | Process for the electrolytic conversion of furan derivatives |
| DE19962102A1 (en) * | 1999-12-22 | 2001-06-28 | Basf Ag | Process for the electrochemical oxidation of organic compounds |
| DE10058304A1 (en) | 2000-11-24 | 2002-05-29 | Basf Ag | Process for the preparation of alkoxylated carbonyl compounds by an anodic oxidation process using the cathodic coupling reaction for organic synthesis |
| US6824599B2 (en) | 2001-10-03 | 2004-11-30 | The University Of Alabama | Dissolution and processing of cellulose using ionic liquids |
| DE102004031025B3 (en) | 2004-06-26 | 2005-12-29 | Thüringisches Institut für Textil- und Kunststoff-Forschung e.V. | Method and device for the production of shaped articles from cellulose |
| JP5371441B2 (en) | 2005-12-23 | 2013-12-18 | ビーエーエスエフ ソシエタス・ヨーロピア | Solvent system based on molten ionic liquid, its production and its use to produce regenerated carbohydrates |
| DE102006022009B3 (en) | 2006-05-10 | 2007-12-06 | Thüringisches Institut für Textil- und Kunststoff-Forschung e.V. | Process for producing cellulosic multicomponent fibers |
| CN101522985B (en) | 2006-10-13 | 2013-01-16 | 巴斯夫欧洲公司 | Ionic liquids for solubilizing polymers |
| EP2411564B1 (en) * | 2009-03-27 | 2017-05-10 | Basf Se | Electrochemical process for producing 3-tert-butylbenzaldehyde-dimethylacetal |
| JP2013519638A (en) * | 2010-02-12 | 2013-05-30 | ビーエーエスエフ ソシエタス・ヨーロピア | Method for producing 4-isopropylcyclohexylmethanol |
| US8889920B2 (en) * | 2010-02-12 | 2014-11-18 | Basf Se | Process for preparing 4-isopropylcyclohexylmethanol |
| MX2013002981A (en) * | 2010-09-16 | 2013-04-05 | Basf Se | Method for producing 2-methyl-3-(4-tert-butylphenyl)-propanal having high para-isomer purity. |
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2013
- 2013-06-05 CA CA2876566A patent/CA2876566A1/en not_active Abandoned
- 2013-06-05 EP EP13729287.6A patent/EP2861785A2/en not_active Withdrawn
- 2013-06-05 JP JP2015516554A patent/JP2015527483A/en not_active Withdrawn
- 2013-06-05 WO PCT/EP2013/061555 patent/WO2013186094A2/en active Application Filing
- 2013-06-05 CN CN201380031601.2A patent/CN104379814A/en active Pending
- 2013-06-05 KR KR20157000674A patent/KR20150023709A/en not_active Application Discontinuation
- 2013-06-14 TW TW102121221A patent/TW201400469A/en unknown
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| CN104379814A (en) | 2015-02-25 |
| TW201400469A (en) | 2014-01-01 |
| WO2013186094A3 (en) | 2014-07-24 |
| WO2013186094A2 (en) | 2013-12-19 |
| EP2861785A2 (en) | 2015-04-22 |
| KR20150023709A (en) | 2015-03-05 |
| JP2015527483A (en) | 2015-09-17 |
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