JP3296885B2 - Method for producing esters - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing esters used in various applications such as fragrances, refrigerator oils, rubbers, inks, paint additives, and the like. It relates to a method of manufacturing.

[0002]

2. Description of the Related Art Conventional esters are disclosed, for example, in JP-A-5-5-5.
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 and 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 producing an ester 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]

In the conventional method for producing esters, when the dehydration reaction between fatty acid and alcohol is performed as described above, the reaction rate is low, and it is necessary to use a high-capacity, large-capacity reactor. In addition, the method using acid chloride requires a complicated process because an acid chloride of an inorganic acid is used. An object of the present invention is to solve the problems of such conventional methods for producing esters and to provide a method for producing esters efficiently and industrially advantageously.

[0005]

As a result of intensive studies on a method for producing an ester having the above-mentioned problems, the inventors have found that an olefin and carbon monoxide can be converted into a catalyst using hydrogen fluoride as a catalyst.
The resulting acyl fluoride is reacted with an alcohol.
By doing so, esters can be obtained at low temperature in a short time,
Distill the reaction product under pressure to contain hydrogen fluoride.
It can be easily recycled and the reaction product
Since the esters can be easily separated by distilling the oil layer to be separated by being introduced into the reactor , the inventors have found that the esters can be obtained extremely efficiently and at low cost, and have reached the present invention.

That is, the present invention relates to a method for preparing pentene in the presence of hydrogen fluoride.
Down, olefins selected from hexene and octene, upon reacting the carbon monoxide and an alcohol to produce the ester, the (1) the presence of hydrogen fluoride, is reacted the olefin <br/> down, carbon monoxide (2) a second step of reacting the acyl fluoride obtained in the first step with an alcohol in the presence of hydrogen fluoride to produce esters, and (3) a second step of producing esters. It has a third step of separating hydrogen fluoride by distilling the reaction product liquid in two steps under pressure, and the hydrogen fluoride obtained in the third step is recycled and used in the first step Process for producing esters and from pentene, hexene and octene in the presence of hydrogen fluoride
Olefin selected, when reacted with carbon monoxide and an alcohol to produce the ester, the (1) the presence of hydrogen fluoride, the first step of producing a acyl fluoride by reacting the olefin, carbon monoxide, (2) In the presence of hydrogen fluoride,
The second step in which the acyl fluoride obtained in the first step is reacted with an alcohol to produce esters, and (3) the reaction product obtained in the second step is put into ice water, and the oil layer to be separated is distilled. A method for producing an ester, comprising a third step of separating the ester.

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, pentaerythritol, Examples include polyhydric alcohols such as ethylene glycol, propylene glycol, glycerol, and sorbidol.

The amount of hydrogen fluoride used in the process of the present invention is 5 to 30 moles, preferably 7 to 15 moles per mole 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 ester decreases. If the molar ratio is higher than 30, the yield is not changed and the reactor becomes large, so that it 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 per mole of the olefin (based on the number of moles of OH groups in the alcohol), and is preferably from 0.7 to 1.5 moles. If the amount of alcohol used is too large, the amount of unreacted alcohol recovered will increase. If the amount of the alcohol used is too small, the reaction product of the olefin and carbon monoxide (acyl fluoride) remains in the reaction product, making it difficult to separate it. The amount of carbon monoxide used in the reaction is determined by the reaction pressure. The reaction pressures described below are for the case where high-purity carbon monoxide is used. If the carbon monoxide gas used contains a considerable amount of inert gas, the partial pressure of carbon monoxide is determined by the reaction pressure. Equivalent to pressure.

[0010] In the present invention, the olefin is reacted with hydrogen fluoride in hydrogen fluoride.
After reacting the carbon oxide, the alcohol is reacted. This
In the method described above, olefin and carbon monoxide are
To give an acyl fluoride,
Acyl reacts with alcohol to produce ester and hydrogen fluoride
It is advantageous because the ester can be obtained in high yield
It is .

The pressure at which the olefin reacts with carbon monoxide in hydrogen fluoride 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. But the pressure is 100 kg / cm
Even if it is higher than ² G, the yield hardly changes and the equipment cost becomes high, so that it is not industrially advantageous.

The reaction temperature between the olefin and carbon monoxide varies depending on the olefin used, but 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 will be low, which is economically disadvantageous.

The reaction of the product of the olefin and carbon monoxide (acyl fluoride) thus obtained with 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 under 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.

Since the reaction product obtained by the method of the present invention is 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 easily separated from hydrogen fluoride by distillation.
This hydrogen fluoride can be recycled. Industrially, hydrogen fluoride can be separated and recovered by distillation under pressure, but depending on the type of ester obtained, the ester product can be obtained by pouring the reaction product liquid into water and separating the oil layer to be separated. You can also get

The resulting ester undergoes an isomerization reaction depending on the type of olefin, so that a mixture of isomers is obtained.
The composition varies depending on the reaction temperature, pressure and the like, and suitable reaction conditions are selected. The ester production method of the present invention can be carried out in a batch system or a continuous system, but the continuous system is industrially advantageous.

[0017]

Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples.

Example 1 Esters were produced using a 2 liter stainless steel autoclave equipped with a stirrer, three inlet nozzles at the top and one outlet nozzle at the bottom, and a jacket capable of controlling the internal temperature. Was. First, after replacing the autoclave with carbon monoxide, 420 g (21 mol) of hydrogen fluoride was introduced. Cool to a temperature of -10 ° C and add 2% with carbon monoxide.
The pressure was increased to 0 kg / cm ² G. While maintaining the same reaction temperature and supplying carbon monoxide so as to maintain the same pressure, 160 g (1.9 mol) of 1-hexene is supplied from the gas phase of the autoclave over about 60 minutes, and after the supply is completed. Stirring was continued for 20 minutes. The amount of carbon monoxide absorbed by the reaction was 39.2 g (1.4 mol) based on the weight difference of the carbon monoxide measuring tank.

Then, the pressure was reduced to normal pressure to purge unreacted carbon monoxide, and 48 g (1.5 mol) of methanol was supplied to the autoclave by a pump over about 30 minutes. Reaction temperature 10
C. and stirred for 2 hours. After completion of the reaction, the reaction product liquid was poured into ice water, and the oil layer was separated. After the obtained oil phase liquid was washed with water, distillation was performed at 20 mmHg to obtain 197 g of a fraction at 50 to 53 ° C. As a result of analyzing this by gas chromatography,
2,2-dimethylpentanoic acid methyl ester 25%, 2-ethyl
It was a methyl ester isomer mixture of 2-methyl-butanoic acid methyl ester 8%, 2-ethylpentanoic acid methyl ester 47% and 2-methylhexanoic acid methyl ester 20%. Ester yield based on 1-hexene equivalent supplied was 72
mol%.

Example 2 An esterification reaction was carried out in Example 1 using ethanol instead of methanol, and an ester fraction was separated in the same manner. As a result, 2,2-dimethylpentanoic acid ethyl ester 25%, 2-ethyl-2-methyl-butanoic acid ethyl ester 8%, 2-ethylpentanoic acid ethyl ester 47%,
214 g of a mixture of four ethyl ester isomers of 20% ethyl methylhexanoate were obtained. The supplied ester yield based on 1-hexene equivalent was 71 mol%.

Example 3 In Example 1, an esterification reaction was carried out using n-propanol instead of methanol, and a hydrogen fluoride solution of the obtained ester was placed in an HF recovery column (55 mm in diameter, 1000 mm in height, 1 mm in diameter). / 2
Inch Teflon-made Raschig ring filling)
Hydrogen fluoride was recovered under reflux of hexane at 2 kg / cm ² G and a tower bottom temperature of 120 ° C. A hexane solution containing the ester and excess propanol was extracted from the bottom of the column, and purified by distillation to obtain 2,2-dimethylpentanoic acid propyl ester 25.
%, 2-ethyl-2-methyl-butanoic acid propyl ester 8%
231 g of a mixture of four kinds of n-propyl ester isomers, propyl ester of 2-ethylpentanoic acid 47% and propyl ester of 2-methylhexanoic acid 20%, were obtained. The supplied ester yield based on 1-hexene equivalent was 71 mol%.

Example 4 In Example 3, an esterification reaction was carried out using trimethylolpropane instead of n-propanol, and a hydrogen fluoride solution of the obtained ester was hydrogenated using the same HF recovery column. And a simple distillation of the liquid at the bottom of the column is carried out to obtain 2-3 mmHg 2
As a fraction at 20 to 230 ° C, gas chromatographic analysis showed that the isomer mixture having a triester purity of 99% or more was obtained.
g. The supplied ester yield based on 1-hexene equivalent was 70 mol%. The physical properties of this isomer mixture are kinematic viscosity 23.6 cst (40 ° C), specific gravity 0.954 (20/20 ° C), hydroxyl value
It was less than 5 mgKOH / g.

Example 5 The reaction between 1-hexene and carbon monoxide in Example 1 was
C. was performed. Esterification reaction and purification of the obtained reaction solution with methanol were performed in the same manner, and analyzed by gas chromatography. As a result, 2,2-dimethylpentanoic acid methyl ester 40%, 2-ethyl-2-methyl-butanoic acid ester 13
%, 2-ethylpentanoic acid methyl ester 32%, and 2-methylhexanoic acid methyl ester 15%, a mixture of methyl ester isomers 184 g were obtained. The supplied ester yield based on 1-hexene equivalent was 67 mol%.

Example 6 The reaction between 1-hexene and carbon monoxide in Example 1 was carried out by 35
C. was performed. Esterification reaction and purification of the obtained reaction solution with methanol were performed in the same manner, and analyzed by gas chromatography. As a result, 2,2-dimethylpentanoic acid methyl ester 53%, 2-ethyl-2-methyl-butanoic acid ester 20
%, 2-ethylpentanoic acid methyl ester 17% and 2-methylhexanoic acid methyl ester 10% were obtained as a mixture of 170 g of methyl ester isomers. The supplied ester yield based on 1-hexene equivalent was 62 mol%.

Example 7 The reaction between 1-hexene and carbon monoxide in Example 1 was carried out as follows:
The test was performed at a pressure of 50 kg / cm ² G and a temperature of −13 ° C. Esterification reaction and purification of the obtained reaction solution with methanol were performed in the same manner, and analyzed by gas chromatography.As a result, methyl 2,2-dimethylpentanoate 13%, 2-ethyl-2-methyl-butanoate were obtained. 4%, 2-ethylpentanoic acid methyl ester 58%, 2-methylhexanoic acid methyl ester 2
219 g of a 5% mixture of methyl ester isomers were obtained. The ester yield based on the supplied 1-hexene equivalent was 80 mol%.

[0025]

As is clear from the examples, in the process of the present invention, olefins, carbon monoxide and alcohols can be obtained at a low temperature and in a short time in a high yield. In the process of the present invention, the reaction rate is high, the reactor is small, and the hydrogen fluoride of the catalyst can be easily separated from the reaction product by distillation and recycled, so that esters are extremely industrially advantageous. Can be manufactured.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Haruichi Matsumoto 3-10 Mizushima Kaigandori, Kurashiki City, Okayama Prefecture Mitsubishi Gas Chemical Co., Ltd. Mizushima Plant (56) References JP-A-58-96039 (JP, A) JP-A-57-9736 (JP, A) JP-T-57-500218 (JP, A) U.S. Pat.

Claims (2)

(57) [Claims] (1) pentene, hexene and pentane in the presence of hydrogen fluoride ;
Olefin selected from fine octene, upon reacting the carbon monoxide and alcohol to produce the ester, (1) the presence of hydrogen fluoride, the producing acyl fluoride by reacting the olefin, carbon monoxide One step, (2) The second step in which the acyl fluoride obtained in the first step is reacted with an alcohol in the presence of hydrogen fluoride to produce esters, and (3) The reaction product liquid of the second step is added. A method for producing esters, comprising a third step of separating hydrogen fluoride by distillation under pressure, wherein the hydrogen fluoride obtained in the third step is recycled to the first step. 2. Penten, hexene and hexene in the presence of hydrogen fluoride.
Olefin selected from fine octene, upon reacting the carbon monoxide and alcohol to produce the ester, (1) the presence of hydrogen fluoride, the producing acyl fluoride by reacting the olefin, carbon monoxide One step, (2) a second step in which the acyl fluoride obtained in the first step is reacted with an alcohol in the presence of hydrogen fluoride to produce esters, and (3) an ice water A method for producing esters, comprising a third step of separating the esters by distilling the oil layer to be poured into the oil and separating the oil.