GB1572294A - Preparation of aromatic carbonates - Google Patents

Description

(54) PREPARATION OF AROMATIC CARBONATES (71) We, GENERAL ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of New York, United States of America of 1 River Road, Schenectady 12305, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to aromatic carbonates and in particular to a process for making an aromatic carbonate.

This invention is related to our co-pending British Patent Applications No. 41324/77 Serial No. 1572291; 41325/77 Serial No. 1572292; 41326/77 Serial No. 1572293 and 41328/77.

Serial No. 1572295.

U.S. Patent 3,114.762, describes the preparation of aliphatic carbonates by the reaction of aliphatic alcohols with carbon monoxide carried out in the presence of a salt of palladium or platinum metal.

U.S. Patent 3,846,468. describes the preparation of carbonic acid esters by the reaction of an alcohol with carbon monoxide and oxygen carried out in the presence of copper complexed with an organic molecule. Although the disclosure of U.S. Patent No. 3846468 suggests that elements such as iron, cobalt and nickel are effective catalysts in the reaction of alcohols with carbon monoxide in the presence of oxygen, it was found that when iron, cobalt or nickel compounds are substituted for the Group VIIIB elements employed in our process for making aromatic carbonates, such carbonates could not be obtained under these conditions.

This invention provides a catalytic aromatic carbonate process which comprises contacting a phenol, carbon monoxide, a base, and a Group VIIIB element selected from ruthenium, rhodium, palladium, osmium, iridium or platinum, and an oxidant comprising an element. a compound or a complex having an oxidation potential greater than that of the said selected Group VIIIB element. Most preferably, at least a portion of the aromatic carbonate product is separated.

The reactants and the resulting reaction products of my process can be illustrated by the following general equations which are furnished for illustrative purposes only since the intermediate (Eq. la, lb, and 1c, or Eq. 2a, 2b and 2c) reaction mechanisms involved in the preparation of aromatic monocarbonates (Eq. 1) and polycarbonates (Eq. 2) may be much more complex: Eq. 1 (intermediate) (a) PdCl2 + 2R'OH + 2R3N + CO

Pd" + R'2CO3 + 2RANH Cl (b) Pd" + 2CuCl2

2 CuCl + PdCl2 (c) 2CuCl + 2R Cl + 1/2 0,

2CuC12 + 2R3N + H20 Eq. 1 (net result) 2R'OH + CO + 1/202

R'2CO3 + H20 Eq. 2 (intermedi'ite) (a) n Pd('l, n R" (()11)2 + 2n R,N + n CO (b) Pd + 2n CuCl2

2nCuCl + nPdCl1 (c) 2n CuCI + 2n ltxNllCl + l/2nO2

2nCu('l + 2nR3N + nH2O Eq. 2 (net result) n R" (OH)2 + nC() -e l/2nO2

wherein R is an alkyl radical (including cycloalkyl), R' is an aryl radical, R" is an arene radical. and n is a number at least equal to 1.

Any nuclearlv hvdroxy substituted aromatic compound can be used in my process and is defined herein and in the appended claims as "a phenol". Illustratively the phenol (or phenolic reactants) can be described by the formula: I. Ra -( OH)x @ wherein R, represents an aromatic radical, where the -OH radical is attached directly to an aromatic ring carbon atom and x is a number being at least equal to 1. advantageously from 1 to 4, and preferably from 1 to 2. The Ra radical can be carbo- or hetero-monocyclic, polycyclic, or fused polycyclic, and can have two or more cyclic systems (monocylic, polycvclic or fused polycyclic systems) which are connected to each other or by bi- or multivalent radicals.

Preferred phenolic reactants are phenols containing from 6 to 3(). and more preferably from 6 to 15 carbon atoms. Illustrative of commercially important phenolic reactants included within the above description are the following: phenol itself (hydroxy benzene), naphthol, ortho-, meta-, or para-cresol, catechol, cumenol, xylenol, resorcinol, the various isomers of dihydroxydiphenyl, the isomers of dihydroxynaphthalene, bis(4 hydroxyphenyl)propane-2,2,α,α'-bis(4-hydroxyphenyl)-p-diisopropylbenzene, 4,4' di'hvdroxy-3 '5.3'5 '-tetrachloro-phenyl-propane-2,2,4,4'-dihydroxy-3,5 ' .5'-tetrachloro- phenyl-propane-2,2 and 4,4-dihydroxy-3,5,3',5'-tetrachloro-phenyl-propane-2,2 and 4,4'dihydroxy-3,5,3',5'-tetrabromo-phenylpropane-2,2,phloroglucinol, and dihydroxy oligomers. for example an oligomer derived from bisphenol-A.

A generally preferred bisphenol that can be used in the process of the invention can be described bv the following formula:

where ij'dependently. each Rl and R is hydrogen, C1-4 alkyl or phenyl. and independently each R' and R4 is hydrogen or C1-4 alkyl. Preferablv. at least one of R3 is hydrogen and the other is hydrogen or C1-4 alkyl, and at least one of R+ is hydrogen and the other is hydrogen or C1-4 alkyl. Preferably R and R are methyl and at least one of R and R4 is hydrogen.

Especially preferred is bis(4-hydroxyphenyl) propane-2,2, also commonly known as "bisphenol-A" (BPA).

Any Group VIII element, defined herein and in the appended claims as "the Group VIIIB element", can be employed subject to the proviso that it is selected from ruthenium, rhodium, palladium, osmium, iridium or platinum. The Group VIIIB elements can be employed in any of their well-known oxidation states as well as their zero valent elemental, i.e. metallic. form.

Illustratively. the Group VIIIB elements can be present in ionic. inorganic or organic compound or complex. forms. The Group VIIIB elements can be employed in oxide. halide. nitrate. sulfate. oxalate. acetate. carbonate. propionate. hydroxide. or tartrate, forms.

The Group VIIIB elements can be emploved in complex form. e.g. with ligands. such as carbon monoxide, nitriles, tertiary amines, phosphines, arsines, or stibines, and illustratively are often represented by those skilled in the art as mono-, di-, or poly- nuclear Group VIIIB element forms. Generally, the dimeric or polymeric forms are considered to contain Group VIIIB atoms bridged by ligands, or halogens. Preferably the Group VIIIB elements form homogeneous mixtures when combined with the phenolic reactants, especially when the process is carried out under liquid phase reaction conditions.

Illustrative of the generally preferred Group VIIIB element compounds or complexes that can be used in my process follow: Ru, RuCl2, RuBr2, RuI2, Ru(CO)2CI2, Ru(C02I2, Ru(CO)4- Cl2, Ru(CO)4Br2, Ru(CO)412, RuCI3, RuBr3, RuI3, Pd, PdCI2, PdBr2, PdI2, [Pd(CO)Cl2]2, [Pd(CO)Br2]2, [Pd(CO)I2]2, (C6H5CN)2PdCl2, PdCl4, Pd(OH)2 (CNC4H9)2, PdI2(CNC6H5)2, Pd(OH)2 (CNCH3OC6H5), Pd(CNC4H9)4, Rh, Rh(CO)Cl2, Rh(CO)Br2, Rh(CO)I2, Rh2Cl2(CO)2, Rh2(CO)4Cl2, Rh2(CO)4Br2, Rh2(CO)4I2, [Rh(CO)2Cl]2, RhCl3, RhBr3, RhI3, Os, Os(CO)3Cl2, Os(CO)3Br2, Os(CO)3I2, Os(CO)4Cl2, Os(CO)4Br2, Os(CO)4I2, Os(CO)8Cl2, Os(CO)8Br2, Os(CO)8I2, OsCl2, OsCl3, OsI2, OsI3, OsBr3, OsBr4 and OsCl4, Ir, IrCl3, IrCl3(CO), Ir2(CO)8, IrCl3, IrBr3, IrCl3, IrBr4, IrI4, Pt, PtCl2, PtBr2, PtI2, Pt(CO)2Cl2, Pt(CO)2Br2, Pt(CO)2I2, Pt(CO)2Cl4, Pt(CO)2Br4, Pt(CO)2I4, Pt(CO)3Cl4, Pt(CO)3Br4, Pt(Co)3I4, and PtCl2(CNC6H5)2.

Illustrative of ligands that can be associated with the Group VIIIB elements in complex form -- other than and, optionally, in addition to carbon monoxide -- include organic tertiary amines, phosphines, arsines and stibine ligands of the following formula: (E)3Q, wherein, independently, each E is selected from the radicals Z and OZ, wherein independently each Z is selected from organic radicals containing from 1 to 20 carbon atoms, and wherein independently each Q is selected from nitrogen, phosphorus, arsenic or antimony. Preferably, the organic radicals are free of active hydrogen atoms, reactive unsaturation, and are oxidatively stable. More preferably, the E groups are alkyl, cycloalkyl and aryl radicals and mixtures thereof, such as alkaryl, aralkyl, alkcycloalkyl containing from 1 to 10 carbon atoms, and even more preferably each E is an aryl group containing from 6 to 10 carbon atoms.

Illustrative of the generally known presently preferred Group VIIIB complexes which contain ligands include the following: RuCl2[P(C6H5)3]4, [Rh(CO)2Cl]2, trans[(C2H5)]2PdBr2, [P(C4H9)3]2PdCl4, [(Cl6H5)3P]3IrCl3(CO), [(C6H5)3As]3IrCl3(CO), [C6H5)3Sb]3IrCl3(CO), [(C6H5)3P]2PtCl2, [(C6H5)3P]2PtF2, [(C6H5)3P]2PtF2(CO)2, and Pt[(C6H5)3P]2(CO)2.

The Group VIIIB element, compounds and/or complexes can be prepared by any method well-known to those skilled in the art including the methods referenced in the following publications: Treatise on Inorganic Chemistrv, Volume II, H. Remy, Elsevier Publishing Co. (1956); Reactions of Transition-Metal Complexes, J.P. Candlin, K.A. Taylor and D.T.

Thompson, Elsevier Publishing Co. (1968) Library of Congress Catalog Card No.

67-19855: Organic Syntheses Via Metal Carbonyls, Vol. 1, I. Wender and P. Pino, Interscience Publishers (1968) Library of Congress Catalog Card No. 67-13965; The Organic Chemistry of Palladium, Vols. I and II, P.M. Maitlis, Academic Press (1971) Library of Congress Catalog Card No. 77-162937; The Chemistry of Platinum and Palladium, F.R. Hartley, Halsted Press (1973); The process can be carried out in the absence of any solvent, e.g. where the phenolic reactant acts as both a reactant and a solvent, however preferably is carried out in the presence of a solvent. and more preferably solvents of the general class: methylene chloride, ethvlene dichloride, chloroform, carbon tetrachloride, tetrachloroethylene, nitro-methane, hexane, 3-methylpentane, heptane, cyclohexane, methylcyclohexane, cyclohexane. isooctane, p-cymene. cumene, decalin, toluene, benzene, diphenylether, dioxane, thiophene, dimethyl sulfide, ethyl acetate, tetrahydrofuran, chlorobenzene, anisol, bromobenzene, o-dichlorobenzene, methyl formate, iodobenzene, acetone, acetophenone, and mixtures thereof.

In general, the process can be carried out in any basic reaction medium, preferably, that provided by the presence of any inorganic or organic base or mixtures thereof.

Representative of basic species which can be employed are the following: elemental alkali and alkaline earth metals: basic quaternary ammonium. quaternary phosphonium or tertiary sulfonium compounds; alkali or alkaline earth metal hydroxides; salts of strong bases and weak acids: and primary, secondary or tertiary amines. Specific examples of the aforementioned are sodium, potassium, and magnesium metals; quaternary ammonium hydroxide, and tetraethyl phosphonium hydroxide; sodium, potassium, lithium, and calcium hydroxide; quaternary phosphonium tertiary sulfonium, sodium, lithium and barium carbonate, sodium acetate, sodium benzoate, sodium methylate, sodium thiosulfate, sodium sulfide, sodium tetrasulfide, sodium cyanide, sodium hydride, sodium borohydride, potassium fluoride, triethylamine, trimethylamine, allyldiethylamine, benzyldimethyl-amine, dioctylbenylamine, dimethylphenethylamine, 1-dimethyl-amino-2phenylpropane, N,N,N', N' -tetramethylenediamine, 2,2,6,6-tetramethylpyridine, Nmethyl piperidine, pyridine, and 2,2,6,6-N-pentamethylpiperidine. Especially preferred bases are sterically hindered amines, e.g. diisopropylmonoethylamine and 2,2,6,6,N pentamethylpiperidine.

Any oxidant can be employed in the herein claimed process subject to the proviso that the oxidant is a compound or complex of a periodic Group IIIA, IVA, VA, VIA. IB, IIB, VIB. VIIB or VIlIB, element and the oxidant has an oxidation potential greater than or more positive than the Group VIIIB element. Typical oxidants for the Group VIIIB elements are compounds of copper, iron, manganese, cobalt, mercury, lead, cerium, uranium, bismuth, or chromium. Of these, copper salts are preferred. The anion of the salt may be a Cl carboxylate, halide, nitrate, or sulfate, and preferably is a halide., e.g., chloride, bromide, iodide, or fluoride. Illustrative of typical oxidant compounds are cupric chloride, cupric bromide, cupric nitrate, cupric sulfate, and cupric acetate. In addition to the compounds described above, gaseous oxygen may be employed as the sole oxidant in the herein claimed process. Typically, compounds or complexes of a periodic Group IIIA, IVA, VA, IB, IIB, VB, VIB, VIIB, and VIIIB element are preferably employed, in conjunction with oxygen, as redox co-catalysts in order to enhance the rate of oxidation of the Group VIIIB metal by gaseous oxygen.

As used herein and in the appended claims, the expression "complexes" includes coordination or complex compounds well-known to those skilled in the art such as those described in Mechanisms of Inorganic Reactions, Fred Basolo and Ralph G. Pearson, 2nd Edition, John Wiley and Sons. Inc. (1968). These compounds are generally defined herein as containing a central ion or atom. i.e. a periodic Group IIA, IVA, VA, VIA. IB, IIB, VIB, VIIB or VIIIB element and a cluster of atoms or molecules surrounding the periodic group element. The complexes may be nonionic, or a cation or anion. depending on the charges carried by the central atom and the coordinated groups. The coordinated groups are defined herein as ligands. and the total number of attachments to the central atom is defined herein as the coordination number. Other common names for these complexes include complex ions (if electrically charged), Werner complexes, coordination complexes or, simply, complexes.

The redox components as a class comprise any compound or complex of a periodic Group IIIA. IVA, VA, IB, IIB, VB. VIB. VIIB and VIIIB, which catalyze the oxidation of the Group VIIIB elements, i.e. ruthenium. rhodium, palladium, osmium, iridium or platinum in the presence of oxygen, from a lower oxidation state to a higher oxidation state.

Any source of oxygen can be employed, e.g. air, gaseous oxygen, or liquid oxygen.

Preferably either air or gaseous oxygen is employed.

Any amount of oxygen can be employed. Preferably the process is carried out under positive oxygen pressure, i.e., where oxygen is present in stoichiometric amounts sufficient to form the desired aromatic mono- or polycarbonate. In general, oxygen pressures within the range of from 0.1 to 500 atmospheres, or even higher, can be employed with good results. Presently preferred are oxygen pressures within the range of from 1/2 to 200 atmospheres.

Any amount of the oxidant can be employed. For example, oxidant to phenol mole proportions within the range of from 0.001:1 or lower to 1000:1 or higher are effective; however, preferably ratios from 0.1:1 to 10:1 are employed to ensure an optimum conversion of phenol to aromatic carbonate. It is essential wherein an oxidant is employed--in the substantial absence of oxygen, i.e. not as a redox co-catalyst component -that the oxidant be present in amounts stoichiometric to carbonate moieties; i.e.,

formed in the preparation of the aromatic carbonates.

Any amount of redox co-catalyst component can be employed. For example, redox catalyst to phenol mole proportions within the range of from 0.0001:1 or lower to 1000:1 or higher are effective: however, preferably ratios of from 0.0001:1 to 1:1, and more preferably 0.001:1 to 0.01:1 are employed.

Any amount of base can be employed. In general, effective mole ratios of base to the Group VIIIB elements are within the range of from 0.00001:1 to 100:1 or higher, preferably from 0.5:1 to 10:1, and more preferably from 1:1 to 2:1. Generally, mole ratios of at least 1:1 enhance both the reaction rate and the yield of aromatic carbonate.

Any amount of the Group VIIIB element can be employed. For example, Group VIIIB element to phenol mole proportions within the range of from 0.0001:1 or lower to 1000:1 or higher are effective; however, preferably ratios of from 0.001 to 0.01 are employed in my catalytic reaction.

Any amount of carbon monoxide can be employed. preferably the process is carried out under positive carbon monoxide pressure; i.e., where carbon monoxide is present in stoichiometric amounts sufficient to form the desired aromatic mono- or polycarbonate. In general. carbon monoxide pressures within the range of from 1/2 to 500 atmospheres, or even higher, can be employed with good results. Presently preferred are CO pressures within the range of from 1 to 200 atmospheres.

Any amount of solvent, preferably inert, can be employed. In general, optimum solvent to phenolic reactant mole proportions are from 0.5:99.5 to 99.5:0.5, preferably from 50:50 to 99:1.

Any reaction temperature can be employed. In general, optimum reaction temperatures are 0 C. or even lower, to 2()0 C, or even higher and more often 0 C to 50"C.

Any reaction time period can be employed. Generally optimum reaction time periods are 0.1 hour or even less to 10 hours or even more.

In one preferred embodiment, after preparation of the aromatic carbonate, at least a portion of any Group VIIIB element, compound or complex is separated from the carbonate, and at least a portion of the Group VIIIB element, compound or complex is oxidized and at least a portion of the oxidized element, compound or complex is recycled in the aromatic carbonate process.

Following some of the procedures described herein, aromatic salicylates can be formed.

These aromatic salicylates. i.e. aromatic compounds which can be defined as "salicylate", can be generically described by the following formula:

wherein Ri, represents an aromatic radical wherein the hydroxyl radical is positioned ortho relative to the carboxylate. i.e.

radical. and Rc represents an aromatic radical. The Rh and Rc radicals can be carbo- or hetero-monocyclic. polycyclic. or fused polycyclic. and can have two or more cyclic systems (monocyclic. polycyclic or fused polycyclic systems) which are directly joined to each other bv single or double valence bonds, or by bi- or multivalent radicals.

The separation and recovery of the salicylates is described in the above-mentioned British Patent Application No. 41328177. Serial No. 1572295.

In order that those skilled in the art may better understand the invention, the following Examples are given which are illustrative of the best mode of this invention, however, these Examples are not intended to limit the invention in any manner whatsoever. In the Examples. unless otherwise specified. all parts are by weight and the reaction products were verified by infrared spectrum. C-13 nuclear magnetic resonance and mass spectrometry.

Example I Preparation of 4.4'-(o;, a-dimethylbenzyl)diphenyl carbonate using p-cumylphenol, carbon monoxide, diisopropyl-monoethylamine, metallic palladium. and copper dibromide.

A reaction pressure vessel was charged with 2.211 g. (10.43 mmol.) of p-cumylphenol, . l26 g. (1.18 mmol.) of palladium metal, i.e. palladium having an oxidation state of zero, 1.330 g. (10.31 mmol.) of diisopropylmonoethylamine, 1.110 g. (5.0 mmol.) of copper dibromide. 20 ml. of methylenedichloride, and sufficient carbon monoxide to charge the vessel to 66 psi. Subsequent workup showed the presence of 0.141 g. (6% yield) of 4,4'-(a, ct-dimethylbenzyl) diphenylcarbonate of the formula

Exelznple II The preparation of 4.4'-(a.a-dimethylbenzyl)diphenyl carbonate using bis(benzonitrile)palla dium( Il)dichloride.

The reaction medium contained 2.28 g. (10.46 mmol.) of p-cumylphenol, 0.3 g. (0.22 mmol.) of bisbenzonitrile-palladium(II)dichloride, 1.342 g. (10.42 mmol.) of diisopropylmonoethylamine, 1.288 g. (5.78 mmol.) of copper dibromide, 20 ml. of methylene chloride, and sufficient carbon monoxide to charge the vessel to 70 psi. The subject product yield was 11% of 4,4'-(α,α-dimethylbenzyl)biphenylcarbonate.

The number of carbonate moieties, i.e.

formed per mole of palladium metal was 5.2, which hereafter is referred to as the Group VIIIB "turnover value" of the reaction.

Example III Preparation of 4,4'-(α,α-dimethylbenzyl)diphenyl-carbonate under carbon monoxide and oxygen pressure.

The reaction medium contained p-cumylphenol, bis-(benzonitrile)palladium(ll) dichloride, diisopropylmonoethyl-amine, and copper dibromide in the following mole proportions: 100.2:15:8. Sufficient carbon monoxide was charged to the vessel to raise the pressure to 31 psi and sufficient oxygen was subsequently added to raise the pressure of the vessel to a total pressure of 62 psi. The product yield was 8% of 4,4'-α,α(dimethyl- benzyl)diphenylcarbonate. The turn over value was 4.

Example IV Preparation of 4,4'-(α,α-dimethylbenzyl)diphenylcarbonate using palladium(I) monocarbonylmonobromide and 2,2,-6,6,N-pentamethylpiperidine as a base.

The reaction vessel contained 2.12 g. (10.0 mmol.) of p-cumylphenol, 1.55 g. (10.0 mmol.) of the 2.2,6,6,N-pentamethylpiperidine , 2.233 g. (10.0 mmol.) copper dibromide, 0.1 g. (0.5 mmol.) of palladium(l) monocarbonylmonobromide, and 20 ml. of methylenechloride. The product yield was 0.60 g. (26 C/c) of aromatic carbonate and 0.54 g. (18C/o) of mono-bromo-p-cumyl-phenol. The turnover value was 5.4.

Example V This procedure. not an Example of this invention, illustrates the attempted preparation of diphenylcarbonate employing the teachings of U.S. 3,846,468, by contacting sodium phenoxide with carbon monoxide in the presence of pyrridine as a base.

The procedure involved the addition of 6.73 g. (0.05 moles) of copper dichloride. 50 ml. of pvridine. and 150 ml. of N.N-dimethylformamide to the reaction medium. The resulting mixture was cooled to -78" C. in a dry ice acetone bath. 11.6 g. (0.10 moles) of sodium phenoxide dissolved in 50 ml. of N,N-dimethylformamide was slowly added to the reaction medium while maintaining the temperature below -50 C. After all of the sodium phenoxide has been added, the mixture was analyzed for evidence of the formation of diphenylcarbonate at the following temperatures. Less than -50 C., -30 C., -10 C., room temperature, +70 C, while carbon monoxide was slowly bubbled through the reaction medium. Gas chromatography of the reaction medium during the entire reaction period showed no aromatic carbonate formation and showed only the starting materials present within the reaction medium. From this experimental data, it was concluded that teachings of U.S. Patent No. 3846468 were not applicable to reactions involving phenolic reactants.

In a preferred embodiment of this invention, set out in Examples V to XV, the process is carried out in the presence of oxygen and a molecular sieve. This embodiment. which is the subject matter of the above-mentioned British Patent Application Serial No. 1572291 No.

41324/77 has been found to provide improved results and so is disclosed also herein, although not essential to the utility of this invention.

Example VI Preparation of 4,4'(α,α-dimethylbenzyl)diphenyl-carbonate under carbon monoxide and oxygen pressure and in the presence of a molecular sieve Type 4A --- a commercial product of Union Carbide Corporation of the general chemical formula 0.96 + 0.04 Na0l.0() Al03-1.92 + 0.09 SiO2 x H2O.

The reaction medium contained p-cumylphenol, bis-(benzonitrile)palladium(ll) dichloride, diisopropylmonoethyl-amine, and copper dibromide in the following mole proportions: 100:2:16:8. Sufficient carbon monoxide was charged to the vessel to raise the pressure to 31 psi and sufficient oxygen was subsequently added to raise the pressure of the vessel to a total pressure of 62 psi. The product yield was 31 % of 4,4' α,α(dimethylbenzyl)diphenylcarbonate. As illustrated by this example, inclusion of a molecular sieve significantly increases the yield of aromatic carbonate as illustrated by the 400% improvement in yield by this Example contrasted with the yield of Example III.

In a preferred embodiment of the invention set out in Examples VII, VIII and XII the process is carried out through the use of a manganese or cobalt complex catalyst. The embodiment, which is the subject matter of the above-mentioned British Patent Application No. 41324/77 Serial No. 1572291 has been found to provide improved results and so is disclosed also herein, although not essential to the utility of this invention.

Example VII Preparation of 4,4'(α,α-dimethylbenzyl)diphenyl-carbonate using p-cumylphenol, carbon monoxide, the 2,2,6,6,N-pentamethylpiperidine and a palladium bromide complex with bis(benzoinoxime) manganese(II) and a molecular sieve.

A reaction vessel was charged with 2.12 g. (0.010 mole) of p-cumylphenol, 0.030 g.

(().()()()l0 moles) of palladium-bromide, 0.051 g. (0.00010 mole) of bis(benzoinoxime) minganese (Il), 0.155 g. (0.0010 mole) of the 2,2,6,6,N-pentamethylpiperidine compound.

.3() ml. of methyl chloride and 2.0 g of a Linde (Registered Trade Mark) Union Carbide 3A molecular sieve which had been activated at 200 C. in vacuo. The type 3A molecular sieve employed is a commercial product of Union Carbide Corporation produced from Type 4A molecular sieves through ionic exchange of about 75% of the sodium ions by potassium.

Carbon monoxide and air were bubbled slowly through the reaction vessel mixture at room temperature for 18 hors. Gas chromatography indicated the presence of 0.495 g.

(22.2% conversion) of the 4,4'-(α,α-dimethylbenzyl)diphenylcarbonate. After 44 hours, reaction product contained 1.23 g. (55% conversion) of the aromatic carbonate.

Examples VIII - XV Following the General Procedure of Example VII, set out hereinbefore, a series of reactions were run employing various oxidants for the preparation of aromatic carbonates in the presence of molecular sieves. Summarized in Table I hereafter are the reaction parameters and products. i.e. the mole proportions of Group VIIIB element : oxidant phenolic reactant base. the percent conversion of the phenolic reactant to aromatic carbonate. the reaction time and the turnover value.

In all of the Examples. the phenolic reactant was p-cumylphenol and the base was 2,2,6.6,N-pentamethylpiperidine. The Group VIIIB element in Examples VII. VIII. IX and XIII was palladium (II) dibromide. and in Examples X, XI and XII was palladium (I) monocarbonyl monobromide. The oxidant employed in each example is tabulated in Table I. Example XIV was a control run analogous to Example VII except that the Group VIII element was excluded from the reaction and the reaction time was extended. It is consequently not an example of the invention.

TABLE I Mole Ratios Turn Example Group Redox Phenolic Percent (%) Reaction Over No. Redox Component VIIIB : Component : Reactant : Base Conversion Time (hr) Value VII Mn(II)(benzoinoxime)2 1 3 100 20 96 44 54 VIII Mn(II)(benzoinoxime)2 1 1 100 10 55 44 95 IX (C4H9N)2Mn(II)Br4 1 3.5 100 35 20 overnight 19 X Mn(II)Br2.4H2O 1 10 100 100 20 165 19 XI Cu(I)Br 1 10 100 20 21 110 20 XII Co(salen)pyridine 1 3 100 15 90 192 89 XIII VBr3 1 3 100 15 1.7 72 0.7 XIV Mn(II)(benzoinoxime)2 0 3 100 20 non-detect- 168 0 able Example XV Preparation of a polycarbonate of bisphenol-A by contacting bis(4hydroxyphenyl)propane-2,2, carbon monoxide, manganese(II)bis(benzoinoxime).

2,2,6,6,N-pentamethylpiperidine, palladium(II)dibromide, oxygen, molecular sieve Type 3A and air.

A 50 ml. three-neck flask was charged with 4.56 g. (20.0 mmol.) of bisphenol-A, 0.62 g.

(4.4 mmol.) of 2,2,6,6,N-pentamethylpiperidine, 0.06 g. (0.20 mmol.) of palladium(II)dibromide, 0.30 g. (0.60 mmol.) to manganese(II)bis(benzoinoxime), 4 g. of molecular sieve Type 3A and 3() ml. of methylene chloride. Carbon monoxide and air were passed through the solution for 42 hours. Reverse phase liquid chromatography showed the pesence of bisphenol-A and bisphenol A- dimers, trimers, pentamers and higher oligomers. An additional 0.06 g. (0.70 mmol.) of palladium(II)dibromide was added and the reaction continued. The Mn number average molecular weight of the polycarbonate was estimated at 2.800 with about a 10% recovery. This example illustrates and demonstrates the utility of the catalytic process in the preparation of polycarbonates of bisphenol-A.

Although the above examples have illustrated various modifications and changes that can be made in the carrying out of my process, it will be apparent to those skilled in the art that other Group VIIIB metals, phenolic compounds, ligands, oxidants, redox components and solvents as well as other reaction conditions can be effected without departing from the scope of the invention.

Claims (24)

WHAT WE CLAIM IS:

1. A process for producing an aromatic carbonate which comprises contacting a phenol. carbon monoxide, a base, a Group VIIIB element selected from ruthenium, rhodium, palladium, osmium, iridium or platinum, and an oxidant comprising an element, a compound or a complex having an oxidation potential greater than that of the said selected Group VIIIB element.

2. A process as claimed in claim 1. wherein said Group VIIIB element is present in an ionic form.

3. A process as claimed in claim 1 or claim 2, wherein said base is a sterically hindered amine.

4. A process as claimed in any one of claims 1 to 3. wherein said Group VIIIB element is associated with a carbon group.

5. A process as claimed in any one of claims 1 to 3. wherein said Group VIIIB element is associated with a halide.

6. A process as claimed in any one of claims 1 to 3, wherein said Group VIIIB element is coordinated with a ligand selected from an arsine, a stibine, a phosphine, a nitrile or a halide.

7. A process as claimed in any of claims 1 to 3, wherein said Group VIIIB element is associated with an inorganic halide compound.

8. A process as claimed in any one of claims 1 to 3, further comprising the step of separating at least a portion of resulting aromatic carbonate product.

9. A process as claimed in any one of claims 1 to 8 in which the Group VIIIB element is palladium.

10. A process as claimed in claim 1 in which the phenol is p-cumylphenol, the base is 2,2,6,6,N-pentamethylpiperidine, the oxidant is oxygen, the Group VIIIB element is palladium in the form of palladium dibromide, and a redox catalyst for the oxidation of the Group VIIIB element is present.

11. A process as claimed in any one of claims 1 to 10, further comprising, after the preparation of the aromatic carbonate, separating at least a portion of any resulting Group VIIIB element. compound or complex from said carbonate. oxidizing at least a portion of said resulting Group VIIIB element. compound or complex and recycling at least a portion of said oxidized element. compound or complex in said aromatic carbonate process.

12. A process according to anyone of claims 1 to 9 and 11, wherein said phenol is a polyphenol.

13. A process according to claim 12, wherein said polyphenol is an aromatic bisphenol of the formula:

wherein independently each R and R is hydrogen, C1-4 alkyl or phenyl and independently each R@ and R4 is hydrogen or C1-4 alkyl.

14. A process as claimed in claim 13, wherein R and R are methyl and at least one of R3 and R4 is hydrogen.

15. A process as claimed in claim 13 or claim 14. wherein the base is a tertiary gamine.

16. A process as claimed in any one of claims 13 to 15, carried out in the presence of an inert solvent.

17. A process according to claim 12, wherein said polyphenol is bisphenol - A.

18. A process according to any one of claims 1 to 9 and 11 wherein said-phenol has the formula: R;, - OH wherein R, represents an aromatic radical and the -OH radical is attached directly to an aromatic ring carbon atom.

19. A process as claimed in claim 18 wherein the base is a tertiarv amine.

20. A process as claimed in any one of claims 18 or 19 carried out in the presence of an inert solvent.

21. A process as claimed in any one of claims 18 to 20 wherein R is selected from carbo- or heteromonocyclic, polycyclic or fused polycyclic aromatic radicals.

22. A process according to any one of claims 18 to 20 wherein said phenol is phenol.

23. A process for preparing an aromatic carbonate as claimed in claim 1 substantially as hereinbefore described in any one of Examples 1 to 1V and V1 to X111 and XV.

24. An aromatic carbonate when produced by a process as claimed in any one of the preceding claims.