JPH07228590A - Production of sucrose fatty acid ester - Google Patents

Abstract

PURPOSE:To obtain a sucrose fatty acid ester industrially, advantageously and in high yield. CONSTITUTION:In a production process in which sucrose and a fatty acid alkyl ester (SE) are reacted in DMSO solvent to obtain a sucrose fatty acid ester, a reaction mixture is allowed to liquid-liquid extraction in the condition of pH3-7 by using an organic solvent and water to obtain an organic solvent solution containing the SE. Then, the organic solvent solution is allowed to liquid- liquid extraction by using water in a continuous counter current extraction and DMSO remaining in the organic solvent solution is removed. The organic solvent solution thus obtained essentially containing no DMSO is concentrated to produce the sucrose fatty acid ester.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention resides in a method for producing sucrose fatty acid ester (hereinafter abbreviated as SE). More specifically, the present invention provides an industrial purification method for industrially advantageously and stably obtaining high-purity SE from a reaction mixture containing SE produced by a solvent method.

[0002]

2. Description of the Related Art SE has excellent surface-active ability, good biodegradability and safety, so it has been used as an additive for foods, cosmetics, pharmaceuticals, kitchen detergents, feeds, resins, etc. In the chemical industry, it is used as a reaction aid for polymerization reaction, oxidation reaction and the like, and is a very useful compound.

As a method for producing SE, N, N-dimethylformamide or dimethylsulfoxide (hereinafter referred to as DM
Abbreviated as SO. ) Etc. in the presence of an alkali catalyst in a reaction solvent such as sucrose and a fatty acid ester such as fatty acid methyl esterification reaction (Japanese Patent Publication No. 35-1310).
2) etc. are known. The reaction mixture obtained by the above method contains a reaction solvent, unreacted sucrose, an alkali catalyst and the like in addition to SE. In order to separate SE from this mixture, liquid-liquid extraction is usually carried out using an organic solvent such as hexane, butyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, and water, mainly SE is put in an organic solvent phase, unreacted sucrose, The reaction solvent is transferred to the aqueous phase, respectively. Then, the organic solvent phase and the aqueous phase are separated, the organic solvent is removed from the SE-containing organic solvent phase by distillation or the like,
A method of recovering SE has been proposed. (Japanese Patent Publication 48-
21927, JP-B-48-35049, JP-A-50-2.
9417, 50-130712, etc.) The above method has many problems to be solved, such as hydrolysis of SE during liquid-liquid extraction, mixing in the aqueous phase, and poor interface formation during extraction. Hard to get,
This is an extremely difficult method for industrial production.

[0004]

DISCLOSURE OF THE INVENTION The present invention produces SE in a DMSO solvent, efficiently separates and recovers unreacted sucrose and DMSO from the obtained reaction mixture, and makes highly purified SE industrially advantageous. The present invention provides an industrial refining method for stable production.

[0005]

In view of the above-mentioned circumstances, the present inventors have made it possible to efficiently produce SE from a reaction mixture when the esterification reaction of sucrose and a fatty acid ester is carried out in a DMSO solvent in the presence of an alkali catalyst. As a result of investigating the method of recovery, the pH of the aqueous phase at the time of extraction was adjusted to a specific range to suppress the decomposition of SE while suppressing the decomposition of SE and DMSO.
And good separation from sucrose, and by combining specific extraction steps, DMSO content of 1pp
It was found that high-purity SE of m or less can be easily recovered, and the present invention has been completed.

According to the present invention, when SE is separated and obtained from a reaction mixture obtained by reacting sucrose and a fatty acid alkyl ester in a DMSO solvent in the presence of an alkali catalyst, first, the reaction mixture having a carbon number of 4 or more is used. The first liquid-liquid extraction process is performed while using an organic solvent composed of alcohol or ketone and water as an extractant while maintaining the pH of the aqueous phase at 3 to 7.5. In this liquid-liquid extraction, SE was added to the organic solvent phase and DMSO
And unreacted sucrose are extracted in the aqueous phase.

Then, the organic solvent solution containing SE obtained in the first liquid-liquid extraction is subjected to a second liquid-liquid extraction treatment by a continuous countercurrent method using water as an extractant, and mixed into the organic solvent solution. The existing DMSO and unreacted sucrose are extracted into the aqueous phase. Highly pure SE can be obtained by removing the organic solvent from the organic solvent solution containing substantially no DMSO obtained in the second liquid-liquid extraction.

The present invention will be described in detail below. In the present invention, the fatty acid alkyl ester used for the reaction with sucrose usually has 6 to 30 carbon atoms, preferably 8 to 2 carbon atoms.
Two saturated or unsaturated fatty acids (eg caproic acid, capric acid, lauric acid, myristic acid, palmitic acid,
Saturated fatty acids such as stearic acid and behenic acid; unsaturated fatty acids such as linoleic acid, oleic acid, linoleic acid, erucic acid and ricinoleic acid) and lower fatty acid alcohols having 1 to 4 carbon atoms (for example, methanol, ethanol, propanol, Butanol and the like). As the fatty acid alkyl ester, one kind or a mixture of two or more kinds in any proportion may be used. The fatty acid alkyl ester is usually used in an amount of 0.1 to 20 mol, preferably 0.2 to 8 mol, per 1 mol of sucrose.

DMSO is used as the reaction solvent from the viewpoint of thermal stability, solubility in sucrose and safety. The amount of the reaction solvent used is usually 20 to 150% by weight, preferably 30 to 80% by weight, based on the total amount of sucrose and fatty acid alkyl ester. The reaction is carried out in the presence of an alkali catalyst, but since the reaction system is substantially non-aqueous, the alkali catalyst exists in a suspended state in the reaction system. As the alkali catalyst, for example, an alkali metal hydride, an alkali metal hydroxide, an alkali metal salt of a weak acid, etc. are effective, and particularly an alkali metal carbonate (for example, potassium carbonate,
Sodium carbonate, etc.) and alkali metal hydroxides are preferred. The amount of these alkali catalysts used is usually 0.001 to 0.1 equivalent relative to the fatty acid alkyl ester.

The reaction temperature is usually selected from the range of 40 to 170 ° C, but the range of 60 to 150 ° C is particularly preferable. The reaction pressure is usually 0.2 to 43 KPa, preferably 0.7 to 32 KPa. The reaction of sucrose and fatty acid alkyl ester is preferably carried out under reflux of the reaction solvent. As a result, alcohol by-produced during the reaction can be easily removed from the reaction system. In addition, the reaction time varies depending on the charged amount of raw materials and the target SE, but is usually 1
It is about 10 hours.

Since sucrose has eight hydroxyl groups, the sucrose fatty acid ester produced is a mixture of monoester to octaester, and the composition of the produced ester can be adjusted depending on the ratio of the raw materials used. The reaction mixture of sucrose and fatty acid ester thus obtained is
It contains DMSO as a reaction solvent, unreacted raw materials, an alkali catalyst and the like. According to the present invention, SE is highly purified from this mixture,
Moreover, it is intended to recover in high yield.

In the present invention, first, the reaction mixture is subjected to a first liquid-liquid extraction under a specific pH condition using a water-immiscible organic solvent and water as an extractant. As a result, SE in the reaction mixture is extracted into the organic solvent phase, and DMSO, unreacted sucrose and the like are extracted into the aqueous phase. In this liquid-liquid extraction, if the DMSO concentration in the reaction mixture is too high, the transfer of DMSO to the aqueous phase tends to be insufficient.

Therefore, when the DMSO concentration in the reaction mixture is high, it is preferable to distill off a part of the DMSO to adjust the concentration in advance. The DMSO is distilled off at a temperature of 60 to 150 ° C. under reduced pressure using, for example, a thin film evaporator. At the end of the reaction between sucrose and fatty acid alkyl ester, DM
By reducing the reflux amount of SO, the concentration of DMSO in the reaction mixture may be adjusted to the range described above. The concentration of DMSO in the reaction mixture used for extraction is 10 to 80.
It is preferably in the range of 20% by weight, especially 20 to 50% by weight.

At the time of extraction, it is necessary to adjust the pH of the aqueous phase to 3 to 7.5. Since the alkali catalyst remains in the reaction mixture, when the liquid-liquid extraction is carried out without neutralizing it, the pH of the aqueous phase becomes 8 or more. In the present invention, by adjusting this pH within a certain range, S
It is possible to suppress the hydrolysis of E, improve the efficient extraction of SE into the organic solvent phase, and improve the liquid separation property between the organic solvent phase and the aqueous phase. When the pH is high, SE is easily hydrolyzed and the distribution of SE into the organic solvent phase does not become high. On the other hand, when it is too low, the stability of unreacted sucrose and DMSO becomes poor.

A suitable pH for extraction is 3 to 7.0,
Particularly, it is 4 to 6.5. Adjustment of pH at the time of extraction may be carried out by adding an acid to the reaction mixture in advance.
Alternatively, the reaction mixture may be mixed with an aqueous acid solution and an organic solvent.

The organic solvent consisting of alcohol or ketone used for extraction is a water-immiscible solvent having 4 or more carbon atoms, preferably 4 to 10 carbon atoms, and usually n-butanol, isobutanol, t-butanol, n-amyl alcohol, isoamyl alcohol, n-hexanol,
Cyclohexanol, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone or the like is used, and among them, n-butanol and isobutanol are preferable. The amount of the organic solvent used relative to the reaction mixture depends on the amount of S in the reaction mixture.
It is usually 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 1 part by weight of E. On the other hand, the water usage rate is
Usually, it is 0.05 to 10 parts by weight, preferably 0.5 to 2 parts by weight, relative to 1 part by weight of the organic solvent. For example, the amount of water is 1 to 10 relative to the sucrose fatty acid ester in the reaction mixture.
wt times, and the amount of organic solvent is 0.5 to 2 with respect to the water.
It is preferable to carry out the first extraction by multiplying by wt. As the water used here, it is preferable in terms of industrial process to use water containing DMSO obtained as the aqueous phase in the second liquid-liquid extraction step described later.

The acid used as a pH adjuster is usually formic acid, acetic acid, propionic acid, oxalic acid, succinic acid,
It is an organic acid selected from benzoic acid, citric acid, maleic acid, malic acid, tartaric acid and lactic acid, and lactic acid and citric acid are preferably used. The amount of the pH adjuster used is such that the above-mentioned aqueous phase pH reaches a predetermined value, and is usually 0.1-3. It is in the range of 0 equivalent, preferably 0.5 to 1.5 equivalent.

The extraction of the reaction mixture in the present invention is preferably carried out in the presence of a salting-out agent for stable operation. In the present invention, since the alkaline catalyst used in the reaction is neutralized with the pH adjuster, a small amount of neutralized salt is present, but it is preferable to add a salting-out agent. Although the type of salting-out agent is arbitrary, alkali metal salts, alkaline earth metal salts and the like of organic acids used for pH adjustment are preferred. SE food,
Safety as an additive for medicines, kitchen detergents, feeds, etc.
From the viewpoints of stability and interface formation during extraction, an alkali salt of citric acid or an alkaline salt of lactate is preferable. Extraction is usually
It is carried out under the condition that the concentration of the salting-out agent is 50 ppm or more, but it is 500 to 300 in view of stable operability and economy.
The range of 0 ppm is preferred.

The apparatus used in the first liquid-liquid extraction in the present invention is usually a mixer-settler extractor, a countercurrent differential type extraction column, a non-stirring stage type extraction column, a stirring stage type extraction column, etc. A mixer-settler type extractor is preferable in terms of economical efficiency and extraction efficiency. This mixer-settler type extraction device
It can be used in multiple stages, and 1 to 3 stages are preferable from the viewpoint of the amount of water used and economical efficiency. The extraction operation temperature is usually lower than the boiling point of the organic solvent under atmospheric pressure, for example, 2
It is 0 to 80 ° C.

After completion of the first liquid-liquid extraction, the SE-containing organic solvent solution and the DMSO-containing aqueous solution are separated and recovered. Most of the unreacted sucrose and neutral salts in the reaction mixture are also extracted in the aqueous phase. In the present invention, the organic solvent solution is further contacted with water to carry out a second liquid-liquid extraction to remove DMSO and the like remaining in the organic solvent solution. In addition,
The pH of the water used in this extraction is usually 3 to 6.5,
It is preferable to add the above pH adjuster.

This second extraction is carried out using a tower type extraction device,
The SE-containing organic solvent solution obtained by the first extraction is used as a light liquid, while water is used as a heavy liquid for continuous countercurrent extraction. The tower-type extraction device used here is usually a Schibel tower, a rotating disk type extraction tower (RDC), an Oldschurashton tower (Mixco tower), a graesser extractor (RT).
L extractor), ARD tower (Rouwer extractor), Kuni tower, pulsating perforated plate tower, oscillating plate tower, alternating pulsating flow type extractor, etc. can be used, but a rotating disc type can be used. An extraction column (RDC) is preferable from the standpoints of DMSO extraction, interface formation, and industrial stability of operation. The number of stages of this rotary disk extraction device is usually 10 or more, and 50 to 200 stages are preferable from the viewpoint of efficiency of removing DMSO remaining in the SE-containing organic solvent solution and industrial economy. The rotation speed of the rotating disk is usually 5 to 50 r.p.m. p. It is about m.
The extraction operation temperature may be about the same as the temperature for the first liquid-liquid extraction. The ratio of the aqueous phase to the organic solvent phase in the second liquid-liquid extraction is usually 0.2 to 5 times by weight. As in the first extraction, it is preferable that the salting-out agent is present in the aqueous phase in an amount of 500 to 3000 ppm.

In the second liquid-liquid extraction, the residual DMSO concentration in the SE-containing organic solvent solution obtained from this step was 5 pp.
It is preferable to operate so as to be m or less, particularly 1 ppm or less. The target SE can be recovered by distilling off the organic solvent from this organic solvent solution. For example, the organic solvent solution is distilled in a distillation column, the organic solvent is distilled off from the top of the column, and the sucrose fatty acid ester is collected from the bottom of the column. The distillation conditions at this time are, for example, a column top temperature of 70 to 80 ° C. and a pressure of 52 to 55 KPa. Further, it is industrially advantageous and preferable to use the aqueous solution containing DMSO or the like recovered in the second liquid-liquid extraction as a part of the extractant used in the first liquid-liquid extraction treatment. The recovered SE can be directly used as a product for various uses, but it may be preferable to further refine it for use as an additive for foods, cosmetics, pharmaceuticals, feeds and the like. For example, when a small amount of organic solvent is a problem, a small amount of organic solvent can be removed by steam distillation or the like. Then, SE containing water after steam distillation can be used as an SE aqueous solution product as an additive for foods, cosmetics, pharmaceuticals and the like.
Further, by concentrating, drying and pulverizing the SE aqueous solution, the DMSO content is 1 ppm or less and the sucrose content is 0.1 ppm.
It is possible to produce highly purified SE in the form of powder that is highly purified under wt%.

[0023]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples as long as the gist thereof is not exceeded. In the following examples and comparative examples, parts and% are based on weight.

Example 1 Synthesis of SE A reactor was charged with 100 parts of sucrose and 321 parts of DMSO and heated to boil DMSO under a pressure of 2.67 KPa. After totally refluxing for 20 minutes, a part of the steam was distilled out of the system to remove water in the system. When about 40 parts of DMSO was distilled out of the system, the distillation of steam outside the system was stopped. The water content of the liquid in the system at this point was about 0.06% by weight. Then add 20 parts of methyl palmitate and about 0.31 part of anhydrous potassium carbonate to the reactor, and add 2.67 KPa.
The reaction was carried out for 3 hours while boiling DMSO at about 90 ° C. under the pressure of 1. The reaction rate of methyl palmitate reached 99% or more.

After the reaction was completed, about 50% aqueous solution of lactic acid was added to about 0.6.
The catalyst was neutralized by adding 8 parts (1.72 equivalent times the catalyst). The composition of the resulting reaction mixture was DMSO70.
%, Unreacted sucrose 19.6%, SE 9.5%, others 0.
It was 9%. When the composition of SE was analyzed by gel permeation chromatography, monoester 81.
It was 0%, diester 16.9%, and triester 2.1%. The reaction rate of methyl palmitate calculated from the residual amount of methyl palmitate analyzed by gas chromatography was 99.7%. This reaction mixture is
Supply to the evaporator, D at 90 ° C under a pressure of 1.73KPa
MSO was evaporated, DMSO 30%, unreacted sucrose 46
%, SE 22%, and other 2%.

First Liquid-Liquid Extraction The above composition and isobutanol and water (potassium lactate 1
(Containing 200 ppm) was supplied to a mixer-settler type extraction device, and extraction was performed at 60 ° C. under normal pressure. Liquid composition: DMSO 7.7%, isobutanol 29%, water 46
%, SE 5.6%, unreacted sucrose 11.7%. The pH of the aqueous phase at this time was 6.3.

Further, instead of water, an aqueous solution recovered from a rotary disk type extraction tower described later (composition: DMSO 10%,
Isobutanol 8%, water 79%, sucrose 2%, SE0.7
%, Other 0.3%), and the liquid composition at this time was DMSO 10.8%, sucrose 9.6%, SE 4.4%, isobutanol 28.8%, water 45.8%, other 0. .6
%Met.

The composition of the isobutanol solution recovered from the mixer settler was DMSO 9.9%, isobutanol 41.8%, water 37.5%, sucrose 2.0%, SE8.
6% and other 0.2%. The extraction rate of SE in this isobutanol solution is calculated to be 99.5%.
The composition of the aqueous solution was 55.1% water, DMSO11.
8%, isobutyl alcohol 14.3%, sucrose 17.9
% And others 0.9%, and pH was 6.4.

Second liquid-liquid extraction Rotating disk type extraction tower (120 extraction stages, rotation speed 20 r.
p. The isobutanol solution obtained above was put into m) from the lower part, water containing 1200 ppm potassium lactate was supplied from the upper part, and countercurrent extraction was carried out at 60 ° C. under normal pressure.
The supply ratio to the tower is 1 part of water to 1 part of isobutanol solution.
81 parts. The composition of the isobutanol solution flowing out from the upper part of the tower was as follows: isobutyl alcohol 60%, water 26%, S
E14%, sucrose 0.1% or less, DMSO 1p
It was pm or less. By isolating the isobutanol solution at a column top temperature of 80 ° C. and a pressure of 55.3 KPq, isobutanol was removed from the column top and high purity SE was obtained from the column bottom.
Was recovered. Sucrose in this SE is 0.1% or less, DMS
O was 1 ppm or less.

Comparative Example 1 When the first extraction was carried out in the same manner as in Example 1 without adding a 50% aqueous lactic acid solution to the mixture after the reaction, the pH of the aqueous phase was 10.2, and , The composition of the isobutanol solution recovered from the mixer-settler is D
MSO 9.9%, isobutanol 41.9%, water 37.
6%, sucrose 2.0%, SE 8.4%, and the SE extraction rate (98.1%) was low.

Example 2 In Example 1, the DMS concentration of the reaction mixture to be subjected to the first liquid-liquid extraction was adjusted to the concentration shown in Table-1.
Each component of the isobutyl alcohol phase (upper phase) and the aqueous phase (lower phase) in the case where the first liquid-liquid extraction was performed in only one stage under the same conditions as in Example 1 by adjusting the amount of O distilled off. Was calculated. The results are shown in Table-1.

[0032]

[Table 1]

From these results, when the DMSO concentration in the reaction mixture used for the first liquid-liquid extraction treatment was high, the distribution of DMSO and unreacted sucrose into the isobutanol phase increased, while the SE into the aqueous phase increased. The distribution rate has risen.

Comparative Example 2 The DMSO solution used in the first liquid-liquid extraction in Example 1 (DM
60 g (containing SO 30% and SE 22%), 113 g of isobutanol and 113 g of water were mixed and stirred at 60 ° C. for 15 minutes, and then allowed to stand for 30 minutes for stratification. The isobutanol solution of the upper phase was concentrated under reduced pressure to remove isobutanol and water, and crude SE was obtained. DMSO of this thing
The content was 12.8%.

Next, water containing 100 g of isobutanol and 1500 ppm of potassium lactate was added to the crude SE obtained above.
00 g was added, the mixture was stirred, allowed to stand and concentrated in the same manner as above, and the DMSO concentration in the obtained SE was measured. As a result, the DMSO content was 5.1%. The same operation was repeated 10 times, but the DMSO concentration in SE was 5 pp.
It did not fall below m. The results are shown in Table-2.

[0036]

[Table 2]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigetomi Kawada 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Kasei Co., Ltd. Yokkaichi factory (72) Inventor Yukio Kazo 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Kasei Co., Ltd. Yokkaichi Factory

Claims (10)

[Claims] 1. A method for obtaining a sucrose fatty acid ester from a reaction mixture obtained by reacting sucrose with a fatty acid alkyl ester using dimethyl sulfoxide as a reaction solvent in the presence of an alkali catalyst, wherein the reaction mixture is an alcohol having 4 or more carbon atoms. Alternatively, using a water-immiscible organic solvent composed of a ketone and water as an extractant, the first liquid-liquid extraction is performed under the conditions of an aqueous phase pH of 3 to 7.5, whereby dimethyl sulfoxide in the reaction mixture is added to the aqueous phase, Extract the sucrose fatty acid ester into the organic solvent phase, and then perform the second liquid-liquid extraction in which the organic solvent solution containing the sucrose fatty acid ester obtained in the first liquid-liquid extraction step is subjected to continuous countercurrent extraction with water. The dimethylsulfoxide remaining in the organic solvent solution was extracted into the aqueous phase by using to obtain an organic solvent solution containing almost no dimethylsulfoxide. A method for producing a sucrose fatty acid ester, which comprises obtaining a sucrose fatty acid ester from a solvent solution. 2. The method according to claim 1, wherein the fatty acid alkyl ester as a raw material is a C1 to C30 saturated or unsaturated fatty acid C1 to C4 alkyl ester. 3. The method according to claim 1, wherein the alkali catalyst is an alkali metal carbonate or hydroxide. 4. The water-immiscible organic solvent used for extraction is n-
The method according to claim 1, which is butanol and / or isobutanol. 5. The method according to claim 1, wherein the pH adjusting agent used for adjusting the pH of the aqueous phase is an organic acid. 6. The method according to claim 1, wherein the aqueous phase containing dimethylsulfoxide obtained in the second liquid-liquid extraction is used as an extractant for the first liquid-liquid extraction. 7. The method according to claim 1, wherein the concentration of dimethyl sulfoxide in the organic solvent solution obtained in the second extraction is 5 ppm or less. 8. The method according to claim 1, 6 or 8, characterized in that the second extraction is carried out in a rotating disk type extraction tower. 9. The method according to claim 1, wherein the organic solvent solution obtained in the second extraction is distilled to distill off the organic solvent from the top and recover the sucrose fatty acid ester from the bottom of the column. 10. The content of dimethyl sulfoxide in the sucrose fatty acid ester recovered by distillation is 1 ppm or less,
The method according to claim 9, wherein the sucrose content is 0.1 wt% or less.