JP3489593B2 - Method for producing esters - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to various uses such as fragrances, jet engine oils, low-temperature greases, heat-resistant engine oils, refrigerator oils, rubbers, inks, and paint additives. The present invention relates to a method for producing esters used, and more particularly, to a method for producing esters from olefin, carbon monoxide and alcohol. [0002] Conventional esters are disclosed, for example, in JP-A-5-5
As described in No. 098, it is produced by heating a fatty acid and an alcohol in the presence of a catalyst to perform a dehydration reaction. As a catalyst used for this dehydration reaction, an acid catalyst such as sulfuric acid or paratoluenesulfonic acid and an organic titanate compound such as tetrapropyl titanate are known. This dehydration reaction is an equilibrium reaction, in which excess alcohol is used and the reaction is promoted by removing generated water from the reaction system. However, the reaction speed is generally slow, and a long time is required to complete the reaction. For example, when an ester is produced from a branched fatty acid such as a neo-acid type, it is necessary to react at a high temperature of 200 ° C. or more for 10 hours or more, and a high-capacity, large-capacity reactor is used. large. In order to avoid such a reaction at a high temperature for a long time, Japanese Patent Application Laid-Open Nos.
No. 1291 proposes a method for producing an ester via an acid chloride. However, such a method of esterification via an acid chloride requires the production of an acid chloride from a carboxylic acid first,
For this purpose, acid chlorides of inorganic acids such as phosphorus trichloride, phosphorus pentachloride and thionyl chloride are used. Acid chlorides of these inorganic acids are difficult to handle and require complicated steps. [0004] The present inventors have previously found that esters can be produced efficiently by reacting an olefin, carbon monoxide and an alcohol in the presence of hydrogen fluoride. (Japanese Patent Application No. 5-143679)
. This method is an industrially advantageous process because esters can be obtained in a high yield at a low temperature and in a short time, and hydrogen fluoride as a catalyst can be recycled. However, the ester is colored during the distillation for recovering hydrogen fluoride, and the organic acid is separated and generated by heating during the distillation purification of the ester to increase the acid value of the ester. Cannot be used for applications such as engine oil. An object of the present invention is to solve the problems of coloration and acid value in producing esters by reacting an olefin, carbon monoxide and an alcohol in the presence of hydrogen fluoride, and to achieve high purity. An object of the present invention is to provide a method for producing esters efficiently and industrially advantageously. The inventors of the present invention have conducted intensive studies on the industrial production of esters having the above-mentioned problems, and as a result, have found that olefins, carbon monoxide and alcohols can be produced in the presence of hydrogen fluoride. The reaction is carried out, and the obtained reaction solution is distilled under reflux of saturated hydrocarbon to recover hydrogen fluoride. Further, the reaction solution is washed with water and purified by distillation, and then subjected to catalytic hydrogenation, whereby the ester is colorless and transparent. And found that the acid value can be reduced, and reached the present invention. That is, according to the present invention, an olefin, carbon monoxide and an alcohol are reacted in the presence of hydrogen fluoride, and hydrogen fluoride is first recovered from the obtained reaction solution by distillation under reflux of saturated hydrocarbon, followed by reaction. This is a method for producing esters, which comprises subjecting the liquid to water washing and distillation purification, and then subjecting the liquid to catalytic hydrogenation treatment. The olefin used as a raw material in the present invention includes propylene, butylene, isobutylene, pentene, hexene, octene and the like. Examples of the alcohol used in the present invention include monohydric alcohols such as methanol, ethanol, propanol, isopropanol, butanol, pentanol, hexanol, heptanol, and octanol, neopentyl glycol, trimethylolethane, trimethylolpropane, and pentaerythritol. Examples include polyhydric alcohols such as ethylene glycol, propylene glycol, glycerol, and sorbitol. The amount of hydrogen fluoride used in the process of the present invention is from 5 to 30 mol, preferably from 7 to 15 mol, per mol of olefin. When the molar ratio of hydrogen fluoride to olefin is lower than 5, the amount of side reaction increases, and the yield of acyl fluoride and esters decreases. If the molar ratio is higher than 30, the yield is not changed and the reactor becomes large, which is not economically advantageous. In the present invention, boron trifluoride can be used together with hydrogen fluoride as a catalyst. The amount of the alcohol used is not more than 2 molar equivalents (based on the number of moles of the OH group of the alcohol) per mole of the olefin, and is preferably 0.7 to 1.5 mol. If the amount of alcohol used is too large, the amount of unreacted alcohol recovered will increase. When the amount of the alcohol used is too small, the yield of the esters decreases. In the method of the present invention, an olefin is reacted with carbon monoxide in hydrogen fluoride and then an alcohol is reacted. The olefin is supplied and reacted in the presence of hydrogen fluoride, carbon monoxide and alcohol. A method or a method of simultaneously supplying and reacting an olefin and an alcohol in the presence of hydrogen fluoride and carbon monoxide can be performed, and the method is not limited. In the method of reacting an olefin with carbon monoxide in hydrogen fluoride and then reacting with an alcohol, acyl fluoride is obtained by reacting the olefin with carbon monoxide in hydrogen fluoride. It is believed that the reaction between the acyl fluoride and the alcohol produces an ester and hydrogen fluoride, which is generally advantageous in that the ester can be obtained in high yield. When the olefin is reacted with carbon monoxide in hydrogen fluoride by the method described above, the pressure is 100 kg / cm ² G or less, preferably 10 to 80 kg / cm ² G. When the reaction pressure is low, the yield of acyl fluoride is low. However, even if the pressure is higher than 100 kg / cm ² G, the yield hardly changes, and the equipment cost increases, which is not industrially advantageous. The amount of carbon monoxide used in the reaction between the olefin and carbon monoxide is determined by the reaction pressure. The reaction pressure is for high-purity carbon monoxide.If the carbon monoxide gas used contains a considerable amount of inert gas, the partial pressure of carbon monoxide corresponds to the reaction pressure. I do. The reaction temperature between the olefin and carbon monoxide varies depending on the olefin used, but it is generally -30 to 70.
° C, preferably -20 to 50 ° C. If the reaction temperature is too high, by-products increase and the yield decreases. If the reaction temperature is too low, the reaction rate is too low, which is economically disadvantageous. The reaction between the product of the olefin thus obtained from carbon monoxide (acyl fluoride) and the alcohol may be carried out under pressure or at normal pressure. Therefore, the reaction between the olefin and carbon monoxide under pressure is carried out. Alternatively, the reaction may be carried out with the alcohol at the same pressure, or the pressure may be reduced to cause the reaction with the alcohol. The reaction temperature between the product of the olefin and carbon monoxide and the alcohol is -10 to 70C, preferably 0 to 50C. When an olefin is reacted with carbon monoxide in the presence of hydrogen fluoride, an isomerization reaction occurs depending on the type of the olefin, so that the esters obtained by the esterification reaction are an isomer mixture. Its composition mainly depends on the reaction temperature and pressure of the acyl fluoride synthesis, and suitable reaction conditions are selected. A method of supplying and reacting an olefin in the presence of hydrogen fluoride, carbon monoxide and an alcohol, and a method of simultaneously supplying and reacting an olefin and an alcohol in the presence of hydrogen fluoride and carbon monoxide. Is substantially the same as the operating conditions for reacting olefins and carbon monoxide in hydrogen fluoride, and is appropriately selected according to the types of olefins and alcohols used. Since the reaction product obtained by the method of the present invention becomes a solution of hydrogen fluoride, a solvent is not particularly required in the method of the present invention. However, it is also possible to use solvents which do not adversely influence the reaction, for example saturated hydrocarbons such as hexane, heptane, octane and the like. As a method of using a solvent, for example, there is a method of dissolving an olefin in such a solvent and supplying the solution to a reactor. The reaction product obtained by the method of the present invention is distilled in a distillation column under reflux of a saturated hydrocarbon (hereinafter referred to as an HF recovery distillation column), whereby hydrogen fluoride is easily separated. In addition, hydrogen fluoride can be recycled. When unreacted acyl fluoride is present, an inert saturated hydrocarbon having a higher boiling point than that of acyl fluoride is used in order to collect the unreacted acyl fluoride together with hydrogen fluoride from the top of the column.
Saturated hydrocarbons used include hexane, octane, nonane, decane and the like. The reaction liquid and saturated hydrocarbons are recovered from the bottom of the HF recovery distillation column. The amount of the saturated hydrocarbon used in the HF recovery distillation column is 0.5 to 2.0 per mole of the supplied olefin.
Mole, preferably 1.0 to 1.5 mole. When the molar ratio of the saturated hydrocarbon is lower than 0.5, HF cannot be sufficiently recovered from the top of the column. When the molar ratio is larger than 2.0, the energy consumption required for heating increases, and the recovery amount of the saturated hydrocarbon increases, which is not economical. The distillation temperature of the HF recovery distillation column varies depending on the olefin and saturated hydrocarbon used, but is generally 100 to 250 ° C, preferably 120 to 200 ° C at the bottom of the column. It is advantageous in terms of process to carry out the distillation at normal pressure or under pressure, and it is desirable that the pressure be 0.5 to 1.0 kg / cm ² G. In the present invention, after hydrogen fluoride is recovered from the reaction solution, it is purified by distillation and subjected to catalytic hydrogenation. In the purification step, first, the bottom liquid from the HF recovery distillation column is washed with water and then subjected to distillation. The saturated hydrocarbon used in the HF recovery distillation column is easily separated and recovered by simple distillation and recycled. Next, by purifying and distilling the reaction solution, by-products are removed to obtain an ester. The distillation temperature for recovering the saturated hydrocarbons varies depending on the saturated hydrocarbon used, but is generally 50 to 150 ° C., preferably 60 to 120 ° C. at the bottom of the column. The distillation is preferably carried out under reduced pressure in view of the process, and is preferably carried out at 10 to 60 torr. The distillation temperature for obtaining the ester varies depending on the type of the synthesized ester, but is generally 100 to 300 at the temperature at the bottom of the column.
° C, preferably 150 to 280 ° C. The distillation is preferably carried out under reduced pressure in terms of process.
Desirably torr. In the catalytic hydrogenation, Ru, Pd, N
A hydrogenation catalyst such as i-system is used. The amount of the catalyst used is 0.01 to 0.1 parts by weight per part by weight of the ester to be treated.
It is 30 parts by weight, preferably 0.04 to 0.20 part by weight. When the amount of the catalyst is small, the hydrotreating is not sufficiently performed. Even if the amount of the catalyst is too large, the effect of the hydrotreating does not change and the size of the reactor becomes large, which is not industrially advantageous. The catalytic hydrotreating temperature varies depending on the catalyst used, but is generally from 70 to 110 ° C, preferably from 80 to 100 ° C. If the temperature is too low, the ester will not be sufficiently decolorized,
Further, the acid value does not decrease. When the temperature is too high, the ester becomes colorless and transparent, but the acid value increases. The catalytic hydrotreating pressure varies depending on the catalyst used, but is generally 5 to 15
kg / cm ² G, preferably 7 to 10 kg / cm ² G. If the pressure is too low, the processing speed will be slow and decolorization will not be sufficiently performed. Further, even if the pressure is set to 15 kg / cm ² G or more, the value of the acid value does not change and the equipment cost increases, so that it is not industrially advantageous. Next, the present invention will be described with reference to the drawings. FIG.
FIG. 1 is an example of a flowchart of a method for producing an ester according to the present invention. In the method shown in FIG. 1, first, hydrogen fluoride is supplied to the reactor 5 from the flow channel 1, carbon monoxide is charged to a predetermined pressure from the flow channel 3, and then olefin is supplied from the flow channel 2 to fluorinate. Acyl is synthesized, and after the pressure is returned to normal pressure after synthesis, alcohol is supplied from the flow path 4 to synthesize an ester. Alternatively, an ester can be synthesized by reacting an olefin, carbon monoxide and an alcohol in the reactor 5 in the presence of hydrogen fluoride by the above method. After the ester synthesis, the reaction solution and hydrogen fluoride are introduced into the HF recovery distillation column 8 through the passage 6 through the passage 7. Hydrogen fluoride and saturated hydrocarbon are obtained from the top of the HF recovery distillation column, and the saturated hydrocarbon is returned to the distillation column from the flow path 9. Further, hydrogen fluoride is extracted from the flow path 10 and is circulated and used. The reaction solution and the saturated hydrocarbon are extracted from the channel 11 at the bottom of the tower, and introduced into the washing tank 14. Flow path 12 in cleaning tank
After washing water is supplied from the reactor, the reaction solution is washed with water and allowed to stand for separation.
Wash water is extracted from 13. The washed reaction liquid and saturated hydrocarbon are extracted from the flow path 15. The reaction solution washed with water is first purified by a distillation column (I) 16
Then, low-boiling saturated hydrocarbons are distilled off from the flow path 17 and are recycled to the flow path 7. Ester and high boilers from the bottom
The ester is introduced into the purification distillation column (II) 19, and the ester is distilled off from the top of the column and sent to the hydrotreating tank 24 from the channel 20. High boiling components are extracted from a flow path 21 from the bottom of the purification distillation column (II). In the hydrotreating tank 24, the ester fraction from the flow path 20, the flow path
A catalytic hydrogenation treatment is performed with the catalyst from the channel 22 and the hydrogen from the channel 23, and the ester and the catalyst are extracted from the channel 25 and separated by filtration. Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples. In each example, the acid value was determined by a titration method using an N / 25 potassium hydroxide solution, and the hydroxyl value was determined by pyridine-
Analysis was performed by the acetic anhydride method. The kinematic viscosity was measured with an Ubbelohde viscometer, and the color of the ester was measured with an ASTM color tester. Example 1 Two 1-liter stainless steel autoclaves having a stirrer, three inlet nozzles at the top and one outlet nozzle at the bottom, and a jacket capable of controlling the internal temperature, a tower diameter of 30 mmφ, and a length of Stainless steel distillation column (H) filled with 1000 mm, 1/2 inch Teflon Raschig rings
(F recovery distillation column) and a glass distillation apparatus (for ester distillation) having a capacity of 0.5 L in the pot were used to produce esters. After replacing the autoclave with carbon monoxide, 210 g (10.5 mol) of hydrogen fluoride was introduced. Cool to -18 ° C and add 20 kg / cm ² with carbon monoxide
Pressurized to G While maintaining the same reaction temperature and supplying carbon monoxide to maintain the same pressure, 1-octene 91 g
(0.81 mol) was supplied from the gas phase of the autoclave over about 30 minutes, and after the completion of the supply, stirring was continued for about 20 minutes until no absorption of carbon monoxide was observed. The amount of carbon monoxide absorbed by the reaction is 17.6 g (0.63 g) from the weight difference of the carbon monoxide measuring tank.
Mol). Then, the pressure was reduced to normal pressure, 21.5 g (0.158 mol) of pentaerythritol was supplied to the autoclave over about 30 minutes, and the mixture was stirred at the reaction temperature of 0 ° C. for 2 hours. After the completion of the reaction, the obtained reaction solution and n-decane are supplied to a HF recovery distillation column, and the mixture is distilled at a pressure of 0.5 kg / cm ² G and a bottom temperature of 200 ° C under reflux of n-decane, and fluorinated from the top of the column. Hydrogen was recovered. The ester and n-decane solution were extracted from the bottom of the column and washed. The n-decane was removed by simple distillation, followed by rectification to obtain 103.5 g of a yellow ester fraction. The acid value of the ester fraction measured at this time was 0.055 mgKOH / g. The obtained ester and 17.3 g of a 5% Ru / C catalyst (manufactured by NE-Chem Cat Co., Ltd.) were charged into an autoclave, and stirred at a temperature of 80 ° C. and a hydrogen pressure of 8 kg / cm ² G for 2 hours. After cooling to room temperature, the catalyst was filtered off to obtain 100.5 g of a colorless and transparent liquid. When this was analyzed by gas chromatography, it was an isomer mixture having a tetraester purity of 99% or more, and the yield of the ester relative to the supplied 1-octene was 71.3 mol%. The acid value of the obtained tetraester is 0.012 mgKOH / g, and the kinematic viscosity is 62 cst.
(40 ° C.), the hydroxyl value was 2 mgKOH / g or less, and the color of the ester was L0.5 on an ASTM color tester. Example 2 An ester was produced in the same manner as in Example 1, except that 32.9 g (0.316 mol) of neopentyl glycol was used instead of pentaerythritol. 114.6 g of a yellow ester fraction was obtained by rectification, and the acid value of this fraction was 0.058 mgKOH / g. The obtained ester fraction and N
i / diatomaceous earth catalyst [Ni 50%, Nikki Chemical Co., Ltd., N1
03] Charge 19.1 g to autoclave, temperature 100
The mixture was stirred at 8 ° C. and a hydrogen pressure of 8 kg / cm ² G for 2 hours. After cooling to room temperature, the catalyst was separated by filtration to obtain 113.4 g of a colorless and transparent liquid. When this was analyzed by gas chromatography, it was an isomer mixture having a diester purity of 99% or more.
72.8 mol of ester based on 1-octene fed
% Met. The acid value of the diester was 0.013 mgKOH / g, the kinematic viscosity was 10 cst (40 ° C.), the hydroxyl value was 2 mgKOH / g or less, and the color of the ester was L0.5 on an ASTM color tester. EXAMPLE 3 45.4 g of 1-butene in Example 1 instead of 1-octene
(0.81 mol), the synthesis temperature of the acyl fluoride was set to -13 ° C., and an ester was produced in the same manner except that 26.8 g (0.20 mol) of trimethylolpropane was used instead of pentaerythritol. 73.3 g of a yellow ester fraction was obtained by rectification. The acid value of this fraction is 0.045 mg KOH
/ g. The obtained ester and 12.2 g of a 5% Pd / C catalyst [manufactured by NEChem Cat Co., Ltd.] were charged into an autoclave, and the mixture was stirred at a temperature of 90 ° C. and a hydrogen pressure of 8 kg / cm ² G for 2 hours. After cooling to room temperature, the catalyst was separated by filtration to obtain 71.3 g of a colorless and transparent liquid. When this was analyzed by gas chromatography, it was an isomer mixture having a triester purity of 99% or more. The yield of the ester relative to the supplied 1-butene was 68.5 mol%. The acid value of the triester is
The kinematic viscosity was 13 cst (40 ° C.), the hydroxyl value was 2 mgKOH / g or less, and the color of the ester was L0.5 on an ASTM color tester. Example 4 1-Hexene instead of 1-octene in Example 1
Using 0g (0.81mol), the synthesis temperature of acyl fluoride is -13 ℃
An ester was produced in the same manner except that 26.8 g (0.20 mol) of trimethylolpropane was used instead of pentaerythritol. 90.1 g of a yellow ester fraction was obtained by rectification. The acid value of this fraction is 0.047 mgKOH
/ g or less. The obtained ester and 15.0 g of a 2% Ru / Al catalyst (manufactured by NE-Chem Cat Co., Ltd.) were charged into an autoclave and stirred at a temperature of 80 ° C. and a hydrogen pressure of 8 kg / cm ² G for 2 hours. After cooling to room temperature, the catalyst was filtered off to obtain 89.2 g of a colorless and transparent liquid. When this was analyzed by gas chromatography, the triester purity was 99%.
It was a mixture of the above isomers. The yield of the ester relative to the supplied 1-hexene was 70.4 mol%. The acid value of the triester is 0.013 mgKOH / g and the kinematic viscosity is 22 cst (40
℃), hydroxyl value is less than 2 mgKOH / g, ester color is AS
It was L0.5 on a TM color tester. As is clear from the examples, in the method of the present invention, an ester can be obtained from olefin, carbon monoxide and alcohol at a low temperature and in a short time in a high yield. Further, in the method of the present invention, the acid value of the ester is reduced to 0.02 mgKOH / g or less by the catalytic hydrogenation of the ester fraction, and the ester is decolorized. can do.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an example of a flowchart of a method for producing an ester according to the present invention. [Explanation of symbols] 5 Reactor 8 HF recovery distillation column 14 Washing tank 16 Purification distillation column (I) 19 Purification distillation column (II) 24 Hydrotreating tank

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification code FI C07C 51/58 C07C 51/58 53/42 53/42 (56) References JP-A-56-110645 (JP, A) JP-A JP-A-53-132522 (JP, A) JP-A-51-70713 (JP, A) JP-A-7-238054 (JP, A) JP-A-61-76435 (JP, A) JP-A-2-152946 (JP) JP-A-6-345688 (JP, A) JP-A-56-95146 (JP, A) JP-A-58-96039 (JP, A) JP-A-1-128955 (JP, A) 56-97245 (JP, A) JP 46-35722 (JP, B1) JP 59-500218 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C07C 67/14 C07C 67/60 C07C 69/22 C07C 51/58 C07C 53/42

Claims (1)

(57) [Claim 1] An olefin, carbon monoxide and an alcohol are reacted in the presence of hydrogen fluoride, and hydrogen fluoride is first obtained from the obtained reaction mixture by distillation under reflux of a saturated hydrocarbon. And collect
Next, a method for producing esters, wherein the reaction solution is washed with water and purified by distillation, followed by catalytic hydrogenation.