JPS5821637B2 - Seizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sucrose fatty acid ester.

More specifically, the present invention relates to a method for producing mono-, di- or polyesters of sucrose and fatty acids by transesterification of sucrose and lower alcohol esters of fatty acids.

Sucrose fatty acid ester is a useful nonionic surfactant that is widely known as an edible dispersant, emulsifier, detergent, etc., and the conventional method for producing it is the transesterification reaction between sucrose and fatty acid lower alcohol ester. (Japanese Patent Publication No. 35-13102) in the presence of an emulsifier and propylene glycol at high temperature (
L.I.

Osipow etal, J. Amer,
Oil Chemists'Soc, 44 307.
1967) etc. are known.

However, in the latter method, the reaction is carried out at high temperature,
This method has the disadvantage that sucrose deteriorates and the quality of the product deteriorates.

On the other hand, in the former method, it is necessary to maintain the reaction system at a boiling state in order to carry out the transesterification reaction efficiently, but when using a high-boiling reaction solvent such as dimethyl sulfoxide, the reaction must be carried out under high reduced pressure. There are unavoidable drawbacks.

For example, in order to maintain the reaction system in a boiling state at a reaction temperature of 90° C., a high vacuum of 2211tiHgO is required.

Therefore, it is necessary to have a reaction apparatus that can withstand such high reduced pressure and a cryocooling apparatus for collecting the lower alcohol by-produced in the reaction, and it goes without saying that this is extremely difficult from an industrial perspective.

In addition, raising the reaction temperature to reduce the degree of pressure reduction may lead to unfavorable results such as denaturation of sucrose and decomposition of dimethyl sulfoxide.

As a result of intensive research aimed at improving the above-mentioned difficulties, the present inventors have found that if a small amount of lower alkylbenzenes whose alkyl moiety has 2 or more carbon atoms is present in the reaction system, Raoult's law will normally be applied. The phenomenon of relaxation of the degree of reduced pressure reaching more than twice the theoretical value is observed, and these lower alkylbenzenes easily dissolve in dimethyl sulfoxide in a quantitative system to form a homogeneous solvent system, so a sufficient reaction rate can be obtained. In addition, when these lower alkylbenzenes are distilled off from the reaction system, they do not form an azeotrope with accompanying lower alcohols such as methanol, so these lower alcohols can be easily separated by simple distillation, and the reaction may not be delayed at all. The present invention was achieved by discovering that it can be refluxed into the reaction system without generation.

An object of the present invention is to provide an industrially advantageous method for producing sucrose fatty acid ester using dimethyl sulfoxide as a reaction solvent. When producing a sucrose fatty acid ester by an exchange reaction between sucrose and a fatty acid ester of a lower alcohol having 1 to 4 carbon atoms, a lower alkylbenzene having a total number of carbon atoms in the alkyl moiety of 2 or more is added to the reaction system relative to dimethyl sulfoxide. This is easily achieved by the presence of less than 20% by weight.

In the present invention, the lower alkylbenzenes in which the total number of carbon atoms in the alkyl moiety is 2 or more are preferably 4 or less, because if the total number of carbon atoms is too large, the benefit of lowering the boiling point is lost. Examples of the isomers include ethylbenzene, propylbenzene, methylethylbenzene, diethylbenzene, etc., but xylenes, ethylbenzene, or mixtures thereof are particularly preferred in view of industrial availability.

It is necessary that the amount of these lower alkylbenzenes present is less than 20% by weight based on dimethyl sulfoxide.

If this amount is too large, depending on the reaction conditions, the thread may become two liquid phases, significantly prolonging the reaction time.

However, in the present invention, the formation of two liquid phases is observed at the start of the reaction, but this is because the lower alcohol ester of fatty acid as a raw material is difficult to dissolve in the solvent phase. The phase phenomenon disappears during the reaction, usually within about one hour, and the entire reaction can be carried out in a short period of time, within several hours.

Furthermore, if the amount is too small, the benefit of lowering the boiling point cannot be stably obtained, so it is usually selected from a range of 2% by weight or more, more preferably 5% by weight or more.

The type of fatty acid ester as a starting material is not particularly limited, but it is usually a methyl ester, an ethyl ester, a clobyl ester, or a butyl fatty acid whose fatty acid moiety has 2 to 30 carbon atoms, preferably 4 to 22 carbon atoms. Esters or mixtures thereof are used.

Specifically, methyl esters, ethyl esters, flobyl esters, or butyl esters of acetic acid, butyric acid, lauric acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, etc. may be mentioned. I can do it.

The alkali as a catalyst is an alkali metal hydroxide or carbonate such as potassium hydroxide, sodium hydroxide, lithium hydroxide, potassium carbonate, sodium carbonate, lithium carbonate, or sodium methoxide, sodium ethoxide, potassium methoxide. Alkali metal alkoxides such as , etc. are preferably used, but there are no particular limitations.

The reaction temperature is not particularly limited, but a range of 40 to 150°C is usually employed, and a range of 60 to 130°C is particularly preferred.

If the reaction temperature is too low, the reaction rate will be low, and if it is too high, sucrose will deteriorate, dimethyl sulfoxide will decompose, etc., which is not preferable.

The reaction method uses a reactor equipped with a reflux condenser or, if necessary, a fractionation column, and charges a predetermined amount of raw materials, reaction solvent, and catalyst, and heats the reaction system to a predetermined temperature under reduced pressure to bring the reaction system to a boiling state. It is done while maintaining

The reaction solvent and the lower alcohol by-produced in the reaction are fractionated using a reflux condenser or a fractionation column, preferably the former is refluxed into the reaction system, and the latter is distilled out of the reaction system.

The reaction continues until distillation of the by-product lower alcohol stops.

After neutralizing the reaction mixture thus obtained, the reaction solvent is distilled off to obtain a sucrose fatty acid ester.

If further purification is required, it can be easily purified by removing unreacted sucrose and adhering reaction solvent by operations such as extraction and concentration.

Moreover, the distribution of sucrose fatty acid ester (the production ratio of monoester, diester, and polyester) can be easily adjusted by adjusting the charging ratio of sucrose and fatty acid ester.

That is, if the charging ratio of sucrose is increased, the production ratio of monoesters will be high. Conversely, if the charging ratio of sucrose is decreased, the production ratio of diesters and polyesters will be increased.

As described above in detail (according to the method of the present invention, the degree of pressure reduction is significantly relaxed, the load on the apparatus is reduced, and both batch-type reactions and continuous-type reactions can be easily adopted. Moreover, the reaction can be completed in a short time, and the added substances can be reused and the lower alcohol can be easily removed from the reaction system, making it possible to produce sucrose fatty acid esters with great industrial advantage. .

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof.

Example 1 In a 500 rIL reaction flask equipped with a stirrer, thermometer, and reflux condenser (circulating warm water adjusted to 40°C), 6681 sucrose and 38.8 ml methyl stearate were added.
f, 250v dimethyl sulfoxide and 25g mixed xylene (50% xylene isomers, 50% ethylbenzene
) and after raising the temperature to 90℃, the carbonic power IJ O, 72
Add P.

Next, the pressure inside the reaction system was adjusted to 75 gmHg, and the mixture was boiled at a temperature of 90° C. while stirring.

Methanol, a by-product of the reaction, is distilled out of the system, and dimethyl sulfoxide and mixed xylene are condensed and refluxed in a reflux condenser.

At the beginning of the reaction, a part of methyl stearate does not dissolve and forms a single liquid phase, but as the reaction progresses, it gradually dissolves and eventually becomes a homogeneous phase.

The time required for homogenization was 30 minutes.

Stirring is continued to continue the reaction until no more methanol is observed to be distilled out.

The reaction time was 90 minutes including the time required for homogenization.

The reaction mixture was neutralized by adding 1.72% of a 50% by weight aqueous lactic acid solution, and then the mixed xylene and dimethyl sulfoxide were distilled off under reduced pressure at a temperature of 90°C to give 110.2'? A residue was obtained.

The sucrose stearate and unreacted methyl stearate contained in the residue were 64.2f (monoester 36.7P, diester 19.2?, triester 8.3?) and 0.19P, respectively.

Note that sucrose stearate was determined by liquid chromatography, and unreacted methyl stearate was determined by direct gas chromatography.

Comparative Example: 100 g of 0-xylene was added instead of 25 g of mixed xylene, and the degree of vacuum was 115 gI! The reaction was carried out in the same manner as in Example 1 except that Hg was used. As a result, the system did not become homogeneous even after 3 hours, and the amount of sucrose ester produced at that point was only 23.6 g. 28. of methyl stearate.
3P remained unreacted.

In Example 1, when mixed xylene was not used, a sufficient boiling state could not be obtained unless the degree of vacuum in the system was set to 22 miHg.

Examples 2 to 7 - The following table shows the results of reactions conducted in the same manner as in Example 1 by changing the type and amount of lower alkylbenzene, the reaction temperature, the charging ratio of sucrose and methyl stearate, etc.

Examples 8 to 12 The following table shows the results of reactions conducted in the same manner as in Example 1 by changing the type of raw fatty acid ester.

Claims (1)

[Claims] 1. When producing a sucrose fatty acid ester by transesterifying sucrose with a fatty acid ester of a lower alcohol having 1 to 4 carbon atoms in the presence of an alkali catalyst and using dimethyl sulfoxide as a reaction solvent, the carbon of the alkyl moiety is added to the reaction system. A method for producing a sucrose fatty acid ester, characterized in that lower alkylbenzenes having a total number of 2 or more are present in an amount of less than 20% by weight based on dimethyl sulfoxide.