CA1187905A - Process for the preparation of bromohydrins from polyols - Google Patents
Process for the preparation of bromohydrins from polyolsInfo
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- CA1187905A CA1187905A CA000405975A CA405975A CA1187905A CA 1187905 A CA1187905 A CA 1187905A CA 000405975 A CA000405975 A CA 000405975A CA 405975 A CA405975 A CA 405975A CA 1187905 A CA1187905 A CA 1187905A
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
- C07C31/34—Halogenated alcohols
- C07C31/42—Polyhydroxylic acyclic alcohols
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
- C07C29/62—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by introduction of halogen; by substitution of halogen atoms by other halogen atoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C31/00—Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
- C07C31/34—Halogenated alcohols
- C07C31/36—Halogenated alcohols the halogen not being fluorine
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- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
Abstract Bromhydrins are prepared by reacting a polyol with aqueous HBr solution, water being removed during the reaction by distillation and a catalytic amount of a low molecular weight organic acid being employed.
Description
a~1~
A nlmlber of processes for the introduction of bromine into polyols are already known. Processes in which phosphorus bromides or thionyl bromide are employed as the brominating agent or which proceed via a ben~enesulphonate as intermediate are very costly to carry out, require expensive reagents and are, for these reasons, not used industrially.
Other processes, in which anhydrous hydrogen bromide and organic sol-vents, such as toluene or perchloro0thylene, are employed, require large exces-ses of hydrogen bromide and/or the use of high temperatures and/or pressures, in order to obtain reasonably acceptable yields. These processes also have no industrial importance.
Mixtures of hydrogen bromide and glacial acetic acid have also been employed in the past. In these instances, it was found to be necessary to bind the water of reaction by the addition of acetic anhydride or acetyl bromide.
The disadvantage of this is that after the reaction, all hydroxyl groups which have not been substituted by bromine are in the form of acetates, and must first be liberated again in a transesterificatlon reaction.
Processes in which aqueous hydrogen bromide is employed require aqueous solutions of hydrogen bromide with concentrations of HBr higher than the ~8% strength hydrobromic acid commercially available in order to be able to achie-ve good results and acceptable reaction times. This means that the hydro-bromic acid commercially available must first be concentrated by passing through gaseous HBr for such processes. In spite of this~ high reaction temperatures and/or working under pressure in an autoclave are still necessary.
The most favourable processes known at present may be regarded as those in which the polyols are reacted in the presence of large amounts of glacial acetic acicl with 48 to 66% strength aqueous hydrogen bromide solution at normal pressure ~see, for example, J. Org. Chem. 30, 19~5 and 3308 (1965)). The Ge/ksch(Gai) Le A 21 117WCA
q~
disadvantage of th:is is; however, that the bromohydrins obtained are also com-pletely or partly ace-tylated on the hydroxyl groups s-till present, and -the free bromohydrins can only be obtained in a subsequent transesterification reaction.
Eor this, a short~chain alcohol, for example methanolJ and an acid cata]yst are added, and the acetate formed and the excess short-chain alcohol are distilled o-ff. Subsequently, the crude bromohydrin thus ob-tained must s-till be purified by recrystallisation.
The expense of this procedure is obvious from German Offenlegungsschrift 2,440,612. According to Example 1 of this German Offenlegungsschrift~ 40 mols of HBr in the form of a 62% s-trength aqueous solu-tion ar0 reacted with 20 mols of pentaerythritol in the presence of 10 mols of acetic acid at about 120C. During the reaction, the water in-troduced with the IIBr solution and formed in the bromination reaction distills off togetiler with some acetic acid. The rest of the acetic acid is bound in the form of acetates to the brominated pentaerythritol. In order to remove these acetate groups from the brominated pentaerythritol, after cooling down, 2 1 of methanol and a catalytic amount of 62% strength HBr solution are added, and -the mixture is then heated to boiling. A mixture of methanol and methyl acetate is distilled off.
Before the excess methanol is completely removed, the mixture is neutralized with methanolic ammonia solution. Subsequently, active charcoal is addedJ heat-ing is repeated, and the mixture is filtered hot through a filter aid. There-after, the last residues of methanol are removed by evaporation to dryness. The crude product thus obtained is recrystallized from trichloroethvlene. Thus in summary, it is clear that the after-treatment of the reaction product involves more outlay than the actual bromination.
A process for the preparation of bromohydrins by reaction of a polyol of the formula _ 3 _ '~
110- Cli2 0-C~12-C-R
~10- Cl-l R = ~12O~1, C113 ~r C2 5 with aqueous HBr solution in the presence of organic acids, wa-ter being removedby distillation during the reaction, has now been found, which is characterised in -tha-t a catalytic amount of a low molecular weight organic acid is employed.Suitable polyols for use in the process according -to the invention are pentaerythritol, trimethylolethane and trimethylolpropane. In these compounds, depending on the amount of 11Br solution employed, one or more OH groups can be replaced by bromine and, in this manner, the corresponding mono- or poly-bromohydrins or mixtures thereof can be obtained. The polyols to be employed may have been prepared in any desired manner and may be employed in commerciallyavailable purity.
The concentration of the aqueous HBr solution ca11 vary within wide limits. For economic reasons, the use oE readily available aqueous HBr solu--tions is preferred, for example those with contents of HBr in the range from 20to 50% by weight. However, 11Br solutions of lower and higher concentration can also be employed. In a preferred manner, 40 to 50% by weight aqueous HBr solu-tions are employed, and particularly preferably the commercially available, approximately ~% by weight aqueous HBr solution. The necessary reaction times can vary depending on the concentration of the HBr solution employed.
The amount of HBr solution substantially depends on the number of O11 groups to be reacted. For example, 0.9 to 2.0 mols of 1-1Br can be employed per mol of OH group to be reacted. In a preferred manner) l.0 to 1.25 mols of HBr are employed per mol o-f OH group to be reacted.
Examples of suitable reaction temperatures are -those in the range from - ~ -20 to 16n C. In a preferred manner, the process is carried out at 80 to 150 C.
It is also possible to proceed in such a manner that the reac-tion starts at relatively low temperatures, for example at room temperature, and then increases to hig}ler temperatures, for example ~0 to l50C.
Tlle pressure is selected so that water formed during the reaction and other water p-resent, particularly tha-t introduced with the ilBr solution~ dis-tills off. During this, the organic acid employed and excess ilBr, if present, may wholly or partly, particularly towards the end of the reaction, also be car-ried over. In a preferred manner, this removal by distillation is carried out over a column. Depending on the reaction temperature used, the pressures can be in the range from, for example, 0.2 to 2 bar, preferably in the range 0.3 to 1.5 bar. The process is particularly preferclbly carried out at normal pressure and the water is distilled over at about 100 C, bottom temperatures in the range from about 110 to 130 C then arising.
I-t is an important charact0ristic of the process according to the invention that, in contrast -to processes hitherto known, it is not carried out in an acetic acid medium, but only using a catalytic amount of a low molecular weight organic acid. Examples of suitable low molecular weight organic acids are carboxylic acids with 1 to 4 C atoms e.g. C3 and C~ carboxylic acids, in which the alkyl hydrogen atoms can also be partly or totally replaced by halogen atoms. Examples which may be mentioned are: formic acid, acetic acid, pro-pionic acid, n-butyric acid, i-butyric acid, monochloroacetic acid, dichloro-acetic acid, trichloroacetic acid, monochloropropionic acid, dichloropropionic acid, monofluoroacetic acid, difluoroacetic acid and trifluoroacetic acid.
Acetic acid is preferably employed.
The amount of low molecular weight organic acid employed can, for example, be 0.1 to 3% by weight relative to the total weight of the reaction batch. This amount is preferably 0.1 to 2% by weight.
- 5 ~
The reac-tion time :Eor the reaction according to the inven-tion is generally between 5 and 20 hours. The reaction time particularly depends on -the amoun-t of low molecular weight organic acid employed, on the nature of the low molecular weight organic acid, on the concentration o-E the aqueous ilBr solution and on -the rate at which the water is distilled off.
~ he process according to the invention can be carried out discontinu-ously o:r continuously. A reaction cascade is suitable, :Eor example, for carry-ing it out continuously.
In a preferred embodiment oE the process according -to the invention, pentaerythritol, trimethylolethane or trimethylolpropane is reacted, after the addition of 0.1 to 2% by weight of acetic acid, relative to the total weight of the reaction batch, with commercially available approximately ~8% strengtll aqueolls ilBr solution in a reaction vessel which is prov:ided with a packed column with reflux divider. 1.0 to 1.25 mols of HBr are employed per mol of OH groups to be reacted. The contents of the reaction vessel are heated at normal pres-sure to about 120 to 130C, and -the heat supply and reflux ratio are controlled in such a manner that, at the top of the column, initially at 100C, only water can be taken o:Ef. Towards the end of the reaction, the take-off temperature is allowed to rise to about 120C. Obviously it is also possible to work under ~0 reduced pressure and with correspondingly lower distillation temperatures. In this way, up to 90% o-E the acetic acid employed and residues of unreacted HBr are carried over in addition to water.
Bromohydrins are obtained in the process according to ~he invention in yields of about 85 to 90% of theory. The product obtained generally contains small amounts of by-products, principally bromohydrins having either one atom of bromine more or one atom less. Frequently, it can be used immediately as it is obtained. If purer products are desired, purification can be carried out, for example, by distillation in vacuo; this however does not generally succeed in completely removing by-products Bromohydrins of high puri~y ~more than 99%
pure) can be obtained i~y recrystallization for example -Erom trichloroethylene or chlorofo-rm.
The process according to the invention offers, in particular, the Eollowing advantages compared to -the processes of the sta-te of the art: the bromohydrins are produced in such purity that there is no need for further puri-fication a:Eter removal from the reaction mixture by distillation. The trarls-esterification reaction with an alcohol which was hitherto necessary, and followed the actual reaction is omitted and this saves one reaction step.
Furthermore7 only a very small amount of organic acid is required.
It must be regarded as exceptionally surprising that, according to the invention, it is possible to obtain such goocl results with only very small amounts of organic acids, since substantially larger amo~m-ts of acetic acid had hitherto been considered necessary.
The bromohydrins which may be prepared according -to the invention are known products, which can be used in a known manner for the flameproofing of plas-tics ~see, for example, European Published Specification 0,018,176)~
In addition, the bromohydrins prepared according to the invention may be readily modified. In this way, for example, they find many uses in the form of their carboxylation products, carboxylates, phosphates and carbonates as flameproofing agents ~see, for example, German Published Offenleg-ungsschriften
A nlmlber of processes for the introduction of bromine into polyols are already known. Processes in which phosphorus bromides or thionyl bromide are employed as the brominating agent or which proceed via a ben~enesulphonate as intermediate are very costly to carry out, require expensive reagents and are, for these reasons, not used industrially.
Other processes, in which anhydrous hydrogen bromide and organic sol-vents, such as toluene or perchloro0thylene, are employed, require large exces-ses of hydrogen bromide and/or the use of high temperatures and/or pressures, in order to obtain reasonably acceptable yields. These processes also have no industrial importance.
Mixtures of hydrogen bromide and glacial acetic acid have also been employed in the past. In these instances, it was found to be necessary to bind the water of reaction by the addition of acetic anhydride or acetyl bromide.
The disadvantage of this is that after the reaction, all hydroxyl groups which have not been substituted by bromine are in the form of acetates, and must first be liberated again in a transesterificatlon reaction.
Processes in which aqueous hydrogen bromide is employed require aqueous solutions of hydrogen bromide with concentrations of HBr higher than the ~8% strength hydrobromic acid commercially available in order to be able to achie-ve good results and acceptable reaction times. This means that the hydro-bromic acid commercially available must first be concentrated by passing through gaseous HBr for such processes. In spite of this~ high reaction temperatures and/or working under pressure in an autoclave are still necessary.
The most favourable processes known at present may be regarded as those in which the polyols are reacted in the presence of large amounts of glacial acetic acicl with 48 to 66% strength aqueous hydrogen bromide solution at normal pressure ~see, for example, J. Org. Chem. 30, 19~5 and 3308 (1965)). The Ge/ksch(Gai) Le A 21 117WCA
q~
disadvantage of th:is is; however, that the bromohydrins obtained are also com-pletely or partly ace-tylated on the hydroxyl groups s-till present, and -the free bromohydrins can only be obtained in a subsequent transesterification reaction.
Eor this, a short~chain alcohol, for example methanolJ and an acid cata]yst are added, and the acetate formed and the excess short-chain alcohol are distilled o-ff. Subsequently, the crude bromohydrin thus ob-tained must s-till be purified by recrystallisation.
The expense of this procedure is obvious from German Offenlegungsschrift 2,440,612. According to Example 1 of this German Offenlegungsschrift~ 40 mols of HBr in the form of a 62% s-trength aqueous solu-tion ar0 reacted with 20 mols of pentaerythritol in the presence of 10 mols of acetic acid at about 120C. During the reaction, the water in-troduced with the IIBr solution and formed in the bromination reaction distills off togetiler with some acetic acid. The rest of the acetic acid is bound in the form of acetates to the brominated pentaerythritol. In order to remove these acetate groups from the brominated pentaerythritol, after cooling down, 2 1 of methanol and a catalytic amount of 62% strength HBr solution are added, and -the mixture is then heated to boiling. A mixture of methanol and methyl acetate is distilled off.
Before the excess methanol is completely removed, the mixture is neutralized with methanolic ammonia solution. Subsequently, active charcoal is addedJ heat-ing is repeated, and the mixture is filtered hot through a filter aid. There-after, the last residues of methanol are removed by evaporation to dryness. The crude product thus obtained is recrystallized from trichloroethvlene. Thus in summary, it is clear that the after-treatment of the reaction product involves more outlay than the actual bromination.
A process for the preparation of bromohydrins by reaction of a polyol of the formula _ 3 _ '~
110- Cli2 0-C~12-C-R
~10- Cl-l R = ~12O~1, C113 ~r C2 5 with aqueous HBr solution in the presence of organic acids, wa-ter being removedby distillation during the reaction, has now been found, which is characterised in -tha-t a catalytic amount of a low molecular weight organic acid is employed.Suitable polyols for use in the process according -to the invention are pentaerythritol, trimethylolethane and trimethylolpropane. In these compounds, depending on the amount of 11Br solution employed, one or more OH groups can be replaced by bromine and, in this manner, the corresponding mono- or poly-bromohydrins or mixtures thereof can be obtained. The polyols to be employed may have been prepared in any desired manner and may be employed in commerciallyavailable purity.
The concentration of the aqueous HBr solution ca11 vary within wide limits. For economic reasons, the use oE readily available aqueous HBr solu--tions is preferred, for example those with contents of HBr in the range from 20to 50% by weight. However, 11Br solutions of lower and higher concentration can also be employed. In a preferred manner, 40 to 50% by weight aqueous HBr solu-tions are employed, and particularly preferably the commercially available, approximately ~% by weight aqueous HBr solution. The necessary reaction times can vary depending on the concentration of the HBr solution employed.
The amount of HBr solution substantially depends on the number of O11 groups to be reacted. For example, 0.9 to 2.0 mols of 1-1Br can be employed per mol of OH group to be reacted. In a preferred manner) l.0 to 1.25 mols of HBr are employed per mol o-f OH group to be reacted.
Examples of suitable reaction temperatures are -those in the range from - ~ -20 to 16n C. In a preferred manner, the process is carried out at 80 to 150 C.
It is also possible to proceed in such a manner that the reac-tion starts at relatively low temperatures, for example at room temperature, and then increases to hig}ler temperatures, for example ~0 to l50C.
Tlle pressure is selected so that water formed during the reaction and other water p-resent, particularly tha-t introduced with the ilBr solution~ dis-tills off. During this, the organic acid employed and excess ilBr, if present, may wholly or partly, particularly towards the end of the reaction, also be car-ried over. In a preferred manner, this removal by distillation is carried out over a column. Depending on the reaction temperature used, the pressures can be in the range from, for example, 0.2 to 2 bar, preferably in the range 0.3 to 1.5 bar. The process is particularly preferclbly carried out at normal pressure and the water is distilled over at about 100 C, bottom temperatures in the range from about 110 to 130 C then arising.
I-t is an important charact0ristic of the process according to the invention that, in contrast -to processes hitherto known, it is not carried out in an acetic acid medium, but only using a catalytic amount of a low molecular weight organic acid. Examples of suitable low molecular weight organic acids are carboxylic acids with 1 to 4 C atoms e.g. C3 and C~ carboxylic acids, in which the alkyl hydrogen atoms can also be partly or totally replaced by halogen atoms. Examples which may be mentioned are: formic acid, acetic acid, pro-pionic acid, n-butyric acid, i-butyric acid, monochloroacetic acid, dichloro-acetic acid, trichloroacetic acid, monochloropropionic acid, dichloropropionic acid, monofluoroacetic acid, difluoroacetic acid and trifluoroacetic acid.
Acetic acid is preferably employed.
The amount of low molecular weight organic acid employed can, for example, be 0.1 to 3% by weight relative to the total weight of the reaction batch. This amount is preferably 0.1 to 2% by weight.
- 5 ~
The reac-tion time :Eor the reaction according to the inven-tion is generally between 5 and 20 hours. The reaction time particularly depends on -the amoun-t of low molecular weight organic acid employed, on the nature of the low molecular weight organic acid, on the concentration o-E the aqueous ilBr solution and on -the rate at which the water is distilled off.
~ he process according to the invention can be carried out discontinu-ously o:r continuously. A reaction cascade is suitable, :Eor example, for carry-ing it out continuously.
In a preferred embodiment oE the process according -to the invention, pentaerythritol, trimethylolethane or trimethylolpropane is reacted, after the addition of 0.1 to 2% by weight of acetic acid, relative to the total weight of the reaction batch, with commercially available approximately ~8% strengtll aqueolls ilBr solution in a reaction vessel which is prov:ided with a packed column with reflux divider. 1.0 to 1.25 mols of HBr are employed per mol of OH groups to be reacted. The contents of the reaction vessel are heated at normal pres-sure to about 120 to 130C, and -the heat supply and reflux ratio are controlled in such a manner that, at the top of the column, initially at 100C, only water can be taken o:Ef. Towards the end of the reaction, the take-off temperature is allowed to rise to about 120C. Obviously it is also possible to work under ~0 reduced pressure and with correspondingly lower distillation temperatures. In this way, up to 90% o-E the acetic acid employed and residues of unreacted HBr are carried over in addition to water.
Bromohydrins are obtained in the process according to ~he invention in yields of about 85 to 90% of theory. The product obtained generally contains small amounts of by-products, principally bromohydrins having either one atom of bromine more or one atom less. Frequently, it can be used immediately as it is obtained. If purer products are desired, purification can be carried out, for example, by distillation in vacuo; this however does not generally succeed in completely removing by-products Bromohydrins of high puri~y ~more than 99%
pure) can be obtained i~y recrystallization for example -Erom trichloroethylene or chlorofo-rm.
The process according to the invention offers, in particular, the Eollowing advantages compared to -the processes of the sta-te of the art: the bromohydrins are produced in such purity that there is no need for further puri-fication a:Eter removal from the reaction mixture by distillation. The trarls-esterification reaction with an alcohol which was hitherto necessary, and followed the actual reaction is omitted and this saves one reaction step.
Furthermore7 only a very small amount of organic acid is required.
It must be regarded as exceptionally surprising that, according to the invention, it is possible to obtain such goocl results with only very small amounts of organic acids, since substantially larger amo~m-ts of acetic acid had hitherto been considered necessary.
The bromohydrins which may be prepared according -to the invention are known products, which can be used in a known manner for the flameproofing of plas-tics ~see, for example, European Published Specification 0,018,176)~
In addition, the bromohydrins prepared according to the invention may be readily modified. In this way, for example, they find many uses in the form of their carboxylation products, carboxylates, phosphates and carbonates as flameproofing agents ~see, for example, German Published Offenleg-ungsschriften
2,157,214 and 2,701,856).
The following examples illustrate the process according to the inven-tion without restricting it in any way.
_ 7 _ ~xamplas ExamE~le 1 Prepara-tion of 2,2-bis~bromomethyl)propan-1,3-diol 2,720 g (20 mols) of pentaerythritol, 6,800 g of ~8% strength aqueous IIBr solution (40.3 mols) and 150 g of acetic acid were initially introduced into a 10 1 round-bottomed flask, which was provided with a heating mantle, stirrer and a 50 cm-long packed column with a reflux divider. ~fter the temperature at the top of the column had reached 100 to 102C at normal pressure, the water was distilled off at this temperature. The bottom temperature was 125 to 130 C
during this. A:Eter 6 hours, the major part of the water had been taken off.
While the bottom temperature slowly rose to 150C, the reflux ratio was adjustedto 2:1 (2 parts take-off, 1 part reflux). In this way, the last residues of water were distilled off in the next 3 hours. More volatile by-products were then distilled off under water-pump vacuum at 10 mbar together with the last residues of water. :[n this way, 4,460 g of distillate were obtained, which con-tained 100% of the calculated amount of water, 79% of the acetic acid employed and 1.5% of the IIBr employed. In addition, in the distillate there was still about 35 g of volatile organic compounds which were not identified.
The residue was distilled at 120 to 130C in vacuo at 0.2 mbar. In this way, 4,575 g, corresponding to 87% of theory, of a transparent product wereobtained, which immediately crystallized. The product thus obtained had the following composition (determined by HPLC = high pressure liquid chromatography):
2.4% by weight of 2-bromomethyl-2-hydroxymethylpropan-1,3-diol 84.2% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 12.1% by weight of 2,2,2-tris(bromomethyl)ethanol Llle product thus obtained could be used without :turther purification.
E~am~le 2 Comparison example according -to German Offenleg~mgsschrift 2,~40,612, but with ~8% strength aqueous HBr solution 20 mols of hydrogen bromide in the :Eorm of a ~8% strength aqueous solu-tion were mixed with 10 mols of pentaerythritol and 5 mols of glacial acetic acicl and heated to reflux in an apparatus analogous to that in Example 1. The water which had been introduced and that which was produced was taken off at normal pressure at a bottom temperature of 120 to 150 C and a top temperature of101 to 102C in the course of 7 hours. In order to liberate -the brominated pentaerythritol which was present in the form of the acetate, transesterifica-tion with methanol was carried out. For this, after cooling, 1 1 of methanol and 2 ml of ~8% strength HBr solution were adcled~ and the batch was heated to reflux. Then a mixture of methanol and methyl acetate was distilled ofE.
A:Eter 2 hours, the temperature at the top of the column had reached the boilingpoint of methanol. The residue was then cooled down, neu-trali~ed with ~ N
methanolic ammonia solution and 80 g of active charcoal was added. The mixture was heated a further ~5 minutes under reflux and thereafter filtered hot througha filter aid (Microfil)*. The pale yellowish filtrate was then evaporated to dryness. In this way, 2,160 g (82%) of a crude product were ob-tained with the following composition (determined by HPLC):
1% by weight of 2-bromomethyl-2-hydroxymethylpropan-1,3-diol 78% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 20% by weight of 2,2,2-tris(bromomethyl)ethanol.
Exam~
___ Preparation of 2,2-bis(bromomethyl)propan-1,3-diol with propionic acid as the catalyst 10 mols of pentaerythritol and 20 mols of HBr in the form of an * Irade Mark aqueous ~8% strength solution using 2% by weight of propionic acid were reacted in a manner corresponding to that described in Example 1. The total water which had been introduced and which was -formed was distilled off at a top temperature of 100 -to 102 C and a bottom temperature of 120 to 140 C in the course of 7 hours. After distillation of the residue in vacuo, 2,332 g (89% of theory) of a product with the Eollowing composition were obtained ~determined by IIPLC):
1.7% by weight of 2-bromomethyl-2-hydroxymethylpropan-1,3-diol 83.5% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 13.8% by weight of 2,2,2-tris~bromomethyl)ethanol.
xample 4 Preparation of 2,2-bis(bromomethyl)propan-1,3-diol using 24% by weight HBr solu-tion , 680 g of pentaerythritol, 3,400 g of 24% strength aqueous hydrobT~omic acid and 40 g of acetic acid were reacted in the manner described in Example 1.
Af-ter 5 hours reaction time, 2,350 g of water had distilled over. Af-ter the addition oE a further 12 g of acetic acid, the residual water was distilled off in the course of 2 hours. A:Eter distillation of the residue in vacuo, 82% of a product of the :Eollowing composition was obtained (determined by HPLC):
7.9% by weight oE 2-bromomethyl-2-hyclroxymethylpropan-1,3-diol 84.2% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 5.6% by weight of 2,2,2-tris(bromomethyl)ethanol.
Example 5 Preparation of 2-bromomethyl-2-hydroxymethylbutan-l-ol 268 g ~2 mols) of trimethylolpropane were dissolved in 374 g (corres-ponding to 2.2 mols) of 48% strength aqueous hydrobromic acid and 6 g of acetic acid in a 1 l three-neck flask and stirred for about 3 hours at room temperature.
Thereaf~er, tile solution was heated to boiling at 400 mbar and water distilled off over a packed column with a reflux divider up to a bo-ttom temperature of 130C in the course of 5 hours. The residual hydrobromic acid was taken off at 20 mbar~ 394 g of residue remained which contained 80% of 2-bromomethyl-2-hydroxymethylbutan-l-ol by gas chromatographic analysis. 270 g (68% of theory) of the pure compound were obtained by recrystallization from toluene and water.
_xam~e 6 Preparac.ion of 2,2-bis~bromomethyl)butan-1-ol 2,680 g (20 mols) of trimethylolpropane, 8,500 g (50 mols) of 48%
strength aqueous hydrobromic acid and 300 g of acetic acid were mixed in a lO 1 three-neck flask and stirred a* room temperature overnight. Then at 400 mbar,
The following examples illustrate the process according to the inven-tion without restricting it in any way.
_ 7 _ ~xamplas ExamE~le 1 Prepara-tion of 2,2-bis~bromomethyl)propan-1,3-diol 2,720 g (20 mols) of pentaerythritol, 6,800 g of ~8% strength aqueous IIBr solution (40.3 mols) and 150 g of acetic acid were initially introduced into a 10 1 round-bottomed flask, which was provided with a heating mantle, stirrer and a 50 cm-long packed column with a reflux divider. ~fter the temperature at the top of the column had reached 100 to 102C at normal pressure, the water was distilled off at this temperature. The bottom temperature was 125 to 130 C
during this. A:Eter 6 hours, the major part of the water had been taken off.
While the bottom temperature slowly rose to 150C, the reflux ratio was adjustedto 2:1 (2 parts take-off, 1 part reflux). In this way, the last residues of water were distilled off in the next 3 hours. More volatile by-products were then distilled off under water-pump vacuum at 10 mbar together with the last residues of water. :[n this way, 4,460 g of distillate were obtained, which con-tained 100% of the calculated amount of water, 79% of the acetic acid employed and 1.5% of the IIBr employed. In addition, in the distillate there was still about 35 g of volatile organic compounds which were not identified.
The residue was distilled at 120 to 130C in vacuo at 0.2 mbar. In this way, 4,575 g, corresponding to 87% of theory, of a transparent product wereobtained, which immediately crystallized. The product thus obtained had the following composition (determined by HPLC = high pressure liquid chromatography):
2.4% by weight of 2-bromomethyl-2-hydroxymethylpropan-1,3-diol 84.2% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 12.1% by weight of 2,2,2-tris(bromomethyl)ethanol Llle product thus obtained could be used without :turther purification.
E~am~le 2 Comparison example according -to German Offenleg~mgsschrift 2,~40,612, but with ~8% strength aqueous HBr solution 20 mols of hydrogen bromide in the :Eorm of a ~8% strength aqueous solu-tion were mixed with 10 mols of pentaerythritol and 5 mols of glacial acetic acicl and heated to reflux in an apparatus analogous to that in Example 1. The water which had been introduced and that which was produced was taken off at normal pressure at a bottom temperature of 120 to 150 C and a top temperature of101 to 102C in the course of 7 hours. In order to liberate -the brominated pentaerythritol which was present in the form of the acetate, transesterifica-tion with methanol was carried out. For this, after cooling, 1 1 of methanol and 2 ml of ~8% strength HBr solution were adcled~ and the batch was heated to reflux. Then a mixture of methanol and methyl acetate was distilled ofE.
A:Eter 2 hours, the temperature at the top of the column had reached the boilingpoint of methanol. The residue was then cooled down, neu-trali~ed with ~ N
methanolic ammonia solution and 80 g of active charcoal was added. The mixture was heated a further ~5 minutes under reflux and thereafter filtered hot througha filter aid (Microfil)*. The pale yellowish filtrate was then evaporated to dryness. In this way, 2,160 g (82%) of a crude product were ob-tained with the following composition (determined by HPLC):
1% by weight of 2-bromomethyl-2-hydroxymethylpropan-1,3-diol 78% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 20% by weight of 2,2,2-tris(bromomethyl)ethanol.
Exam~
___ Preparation of 2,2-bis(bromomethyl)propan-1,3-diol with propionic acid as the catalyst 10 mols of pentaerythritol and 20 mols of HBr in the form of an * Irade Mark aqueous ~8% strength solution using 2% by weight of propionic acid were reacted in a manner corresponding to that described in Example 1. The total water which had been introduced and which was -formed was distilled off at a top temperature of 100 -to 102 C and a bottom temperature of 120 to 140 C in the course of 7 hours. After distillation of the residue in vacuo, 2,332 g (89% of theory) of a product with the Eollowing composition were obtained ~determined by IIPLC):
1.7% by weight of 2-bromomethyl-2-hydroxymethylpropan-1,3-diol 83.5% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 13.8% by weight of 2,2,2-tris~bromomethyl)ethanol.
xample 4 Preparation of 2,2-bis(bromomethyl)propan-1,3-diol using 24% by weight HBr solu-tion , 680 g of pentaerythritol, 3,400 g of 24% strength aqueous hydrobT~omic acid and 40 g of acetic acid were reacted in the manner described in Example 1.
Af-ter 5 hours reaction time, 2,350 g of water had distilled over. Af-ter the addition oE a further 12 g of acetic acid, the residual water was distilled off in the course of 2 hours. A:Eter distillation of the residue in vacuo, 82% of a product of the :Eollowing composition was obtained (determined by HPLC):
7.9% by weight oE 2-bromomethyl-2-hyclroxymethylpropan-1,3-diol 84.2% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 5.6% by weight of 2,2,2-tris(bromomethyl)ethanol.
Example 5 Preparation of 2-bromomethyl-2-hydroxymethylbutan-l-ol 268 g ~2 mols) of trimethylolpropane were dissolved in 374 g (corres-ponding to 2.2 mols) of 48% strength aqueous hydrobromic acid and 6 g of acetic acid in a 1 l three-neck flask and stirred for about 3 hours at room temperature.
Thereaf~er, tile solution was heated to boiling at 400 mbar and water distilled off over a packed column with a reflux divider up to a bo-ttom temperature of 130C in the course of 5 hours. The residual hydrobromic acid was taken off at 20 mbar~ 394 g of residue remained which contained 80% of 2-bromomethyl-2-hydroxymethylbutan-l-ol by gas chromatographic analysis. 270 g (68% of theory) of the pure compound were obtained by recrystallization from toluene and water.
_xam~e 6 Preparac.ion of 2,2-bis~bromomethyl)butan-1-ol 2,680 g (20 mols) of trimethylolpropane, 8,500 g (50 mols) of 48%
strength aqueous hydrobromic acid and 300 g of acetic acid were mixed in a lO 1 three-neck flask and stirred a* room temperature overnight. Then at 400 mbar,
3 1 of distillate were taken off over a packed column at a reflux ratio of 2:1 in the course of 8 hours. After the major part of the hydrobromic acid had reacted, water was further distilled off at a pressure of l bar up to a bottom temperature of 150C. Portions of product which were also carried over in the distillate and separated out in the collector, were combined with the bottom product beEore the subsequent distillation. Thereafter, the residue was dis--tilled at 135 to l40C in vacuo at 16 mbar. 4,559 g of an oil which slowly cry-stallized were obtained, which contained 90% of 2,2-bis(bromomethyl)butan-1-ol by gas chromatographic analysis.
0 Example _ aration of 2-bromomethyl-2-methylpropan-1,3-diol 480 g (4 mols) of trimethylolethane, 748 g (4.4 mols) of 48% strength aqueous HBr solution and 12 g of acetic acid (1%) were initially introduced into a 2 1 capacity apparatus analogous to that in Example 1. This mixture was stirred at room temperature for 3 hours and then water was taken off at 300 mbar up to a bottom temperature of 130 C. The temperature at the top of the column was about 80C clu:ring this. After 9 hours, all the water had passed over. The remaining product was distilled at 0.7 mbar and a boiling point of 120 to 130C. ~60 g (90%) of 2-bromomet~lyl-2-methylpropan-1,3-diol were obtained, which contained 10% of the corresponding dibrominated compound and about 4% of starting material.
Example 8 Preparation of 2,2,2-tris(bromomethyl)ethanol _ . . _~_ 10 mols (1,360 g) of pentaery-thritol, 37.5 mols of HBr in the form of the aqueous 48% strength solution and 100 g of acetic acid were initially introduced into an apparatus analogous to Example 1. After heating to reflux for 3 hours, water which had been produced and that which had been introduced could be distilled off ata top tem-perature of 100C to 102C. The total amount of water and the excess hydrogen bromide distilled off in the course of the next 9 hours. In this way, 3,985 g of distillate were obtained. The bottom temperature rose from 120C to 145C in this period. After distillation in vacuo at 110C to 120C and 0.5 mbar, 2,95g g (91%) of 2,2,2-tris-(bromomethyl)ethanol were obtained of the following com-position (according to HPLC):
1.5% by weight of 2-bromomethyl-2-hydroxymethylpropan-1,3-diol 9.3% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 88 % by weight of 2,2,2-tris(bromomethyl)ethanol.
Le A 21 117
0 Example _ aration of 2-bromomethyl-2-methylpropan-1,3-diol 480 g (4 mols) of trimethylolethane, 748 g (4.4 mols) of 48% strength aqueous HBr solution and 12 g of acetic acid (1%) were initially introduced into a 2 1 capacity apparatus analogous to that in Example 1. This mixture was stirred at room temperature for 3 hours and then water was taken off at 300 mbar up to a bottom temperature of 130 C. The temperature at the top of the column was about 80C clu:ring this. After 9 hours, all the water had passed over. The remaining product was distilled at 0.7 mbar and a boiling point of 120 to 130C. ~60 g (90%) of 2-bromomet~lyl-2-methylpropan-1,3-diol were obtained, which contained 10% of the corresponding dibrominated compound and about 4% of starting material.
Example 8 Preparation of 2,2,2-tris(bromomethyl)ethanol _ . . _~_ 10 mols (1,360 g) of pentaery-thritol, 37.5 mols of HBr in the form of the aqueous 48% strength solution and 100 g of acetic acid were initially introduced into an apparatus analogous to Example 1. After heating to reflux for 3 hours, water which had been produced and that which had been introduced could be distilled off ata top tem-perature of 100C to 102C. The total amount of water and the excess hydrogen bromide distilled off in the course of the next 9 hours. In this way, 3,985 g of distillate were obtained. The bottom temperature rose from 120C to 145C in this period. After distillation in vacuo at 110C to 120C and 0.5 mbar, 2,95g g (91%) of 2,2,2-tris-(bromomethyl)ethanol were obtained of the following com-position (according to HPLC):
1.5% by weight of 2-bromomethyl-2-hydroxymethylpropan-1,3-diol 9.3% by weight of 2,2-bis(bromomethyl)propan-1,3-diol 88 % by weight of 2,2,2-tris(bromomethyl)ethanol.
Le A 21 117
Claims (10)
1. In a process for the preparation of a bromohydrin by reacting a polyol of the formula wherein R = CH2OH, CH3 or C2H5 with an aqueous HBr solution in the presence of an organic acid and during the reaction removing water formed by distillation, the improvement which comprises carrying out the process in the presence of a catalytic amount of a low molecular weight organic acid.
2. A process according to claim 1, wherein said low molecular weight organic acid is employed in an amount of 0.1 to 3% by weight, relative to the total weight of the reaction mixture.
3, A process according to claim 1, wherein said low molecular weight organic acid is employed in an amount of 0.1 to 2% by weight, relative to the total weight of the reaction mixture.
4. A process according to claim 1, wherein said carboxylic acid is one having 1 to 4 carbon atoms.
5. A process according to claim 1, wherein said carboxylic acid is acetic acid.
6. A process according to claim 1, wherein said carboxylic acid is selected from the group consisting of formic acid, propionic acid, n-butyric acid, i-butyric acid, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monochloropropionic acid, dichloropropionic acid, monofluoroacetic acid, difluoroacetic acid and trifluoroacetic acid.
7. A process according to claim 1, wherein said organic acid is propionic acid.
8. A process according to claim 1, wherein a 20 to 50% by weight aqueous HBr solution is employed.
9. A process according to claim 1, wherein 0.9 to 2.0 mols of HBr is employed per hydroxyl group to be reacted.
10. A process according to claim 1, wherein the reaction is carried out at a temperature from 20 to 160° C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3125338.5 | 1981-06-27 | ||
| DE19813125338 DE3125338A1 (en) | 1981-06-27 | 1981-06-27 | METHOD FOR PRODUCING BROMHYDRINES FROM POLYOLS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1187905A true CA1187905A (en) | 1985-05-28 |
Family
ID=6135518
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000405975A Expired CA1187905A (en) | 1981-06-27 | 1982-06-25 | Process for the preparation of bromohydrins from polyols |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0068282B2 (en) |
| JP (1) | JPS584737A (en) |
| CA (1) | CA1187905A (en) |
| DE (2) | DE3125338A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8403548D0 (en) * | 1984-02-10 | 1984-03-14 | Ici Plc | Chemical process |
| JP2002332280A (en) * | 2001-05-09 | 2002-11-22 | Toagosei Co Ltd | Method for producing oxetane compound |
| CN101016226B (en) * | 2007-02-08 | 2010-09-01 | 宜兴市中正化工有限公司 | Synthetic method and refining for dibromoneopentyl glycol |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2144612A (en) * | 1936-09-10 | 1939-01-24 | Dow Chemical Co | Preparation of glycerol dichlorohydrin |
| US3932541A (en) * | 1971-08-12 | 1976-01-13 | The Dow Chemical Company | Process for the preparation of brominated pentaerythritols |
| US3883581A (en) * | 1973-05-23 | 1975-05-13 | Dow Chemical Co | Preparation of brominated pentaerythritols and esters utilizing certain dibasic acids |
| FR2241535B1 (en) * | 1973-08-23 | 1977-02-25 | Nobel Hoechst Chimie | |
| IL50494A (en) * | 1976-09-16 | 1979-01-31 | Dead Sea Bromine Co Ltd | Process for the preparation of dibromonoeopentyl gycol |
-
1981
- 1981-06-27 DE DE19813125338 patent/DE3125338A1/en not_active Withdrawn
-
1982
- 1982-06-15 DE DE8282105226T patent/DE3262311D1/en not_active Expired
- 1982-06-15 EP EP82105226A patent/EP0068282B2/en not_active Expired
- 1982-06-23 JP JP57106992A patent/JPS584737A/en active Pending
- 1982-06-25 CA CA000405975A patent/CA1187905A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS584737A (en) | 1983-01-11 |
| EP0068282B1 (en) | 1985-02-13 |
| DE3125338A1 (en) | 1983-01-13 |
| DE3262311D1 (en) | 1985-03-28 |
| EP0068282B2 (en) | 1989-03-08 |
| EP0068282A1 (en) | 1983-01-05 |
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