JPH07206889A - Method for producing sucrose fatty acid ester - Google Patents

Abstract

(57) [Summary] [Structure] Dose of sucrose and fatty acid alkyl ester
In the method of producing sucrose fatty acid ester (SE) by reacting in an O solvent, the reaction mixture is subjected to liquid-liquid extraction using an organic solvent and water to obtain an SE-containing organic solvent solution.
Then, most of the organic solvent is removed from this organic solvent solution by azeotropic distillation with water to obtain an aqueous solution of SE. Then, this SE aqueous solution is treated with a thin film evaporator to completely remove the remaining organic solvent. [Effect] Industrially advantageous, highly purified sucrose fatty acid ester is obtained.

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. ) Or the like in the presence of an alkali catalyst in the presence of an alkali catalyst, a method of transesterification between sucrose and a fatty acid ester such as fatty acid methyl (JP-B-35-131
02) and the like are known.

The reaction mixture obtained by the above method is
In addition to SE, it contains a reaction solvent, unreacted sucrose and an alkali catalyst. 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, and SE is mainly separated into an organic solvent phase and unreacted sucrose. , The reaction solvent is transferred to the aqueous phase, respectively. Then, a method of separating the organic solvent phase and the aqueous phase and removing the organic solvent from the SE-containing organic solvent phase by distillation or the like to recover SE has been proposed. (Japanese Patent Publication No. 48-219
27, JP-B-48-35049, JP-A-50-2941
7, 50-130712, etc.)

What is important in this method is that no organic solvent remains in the finally obtained SE.
However, from organic solvent solutions containing SE, foods, cosmetics,
It is extremely difficult to collect SE having an organic solvent content reduced to a level suitable for use in pharmaceuticals and the like.

[0006]

DISCLOSURE OF THE INVENTION The present invention synthesizes SE in a DMSO solvent and efficiently separates and recovers SE from an organic solvent solution containing SE obtained by liquid-liquid extraction of the obtained reaction mixture. The present invention provides an industrial refining method for producing highly purified SE in an industrially advantageous and stable manner.

[0007]

Means for Solving the Problems As a result of various investigations by the present inventors, a method for separating and obtaining SE from a reaction mixture obtained by carrying out an esterification reaction of sucrose with a fatty acid ester in a DMSO solvent , A reaction mixture is subjected to liquid-liquid extraction using an organic solvent consisting of an alcohol or a ketone having 4 or more carbon atoms azeotroping with water and water to obtain an organic solvent solution containing SE, and then the organic solvent solution is added to the top of the distillation column. First, water is supplied to the lower part of the distillation column, the organic solvent is distilled off by azeotropic distillation, and S
By obtaining an aqueous solution of E and evaporating water from this aqueous solution using a thin film evaporator, it was found that highly pure SE containing substantially no organic solvent can be stably recovered,
The present invention has been completed.

The present invention will be described in detail below. The fatty acid alkyl ester used for the reaction with sucrose in the present invention usually has 6 to 30 carbon atoms, preferably 8 to
22 saturated or unsaturated fatty acids (eg caproic acid,
Saturated fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid; unsaturated fatty acids such as linoleic acid, oleic acid, linoleic acid, erucic acid, ricinoleic acid) and C1-C4 Lower aliphatic alcohols (eg, methanol, ethanol,
Ester with propanol, butanol, etc.). 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 0.1 to 2 per mol of sucrose.
It is used in an amount of 0 mol, more preferably 0.2 to 8 mol.

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 based on the total amount of sucrose and fatty acid alkyl ester,
It is preferably 30 to 80% by weight.

The reaction is carried out in the presence of an alkali catalyst,
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 (eg potassium carbonate, sodium carbonate etc.)
Is 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. Further, the reaction time varies depending on the charged amount of raw materials and the target SE, but usually,
It is about 1 to 10 hours.

Since sucrose has eight hydroxyl groups, the SE produced is theoretically a mixture of monoester and octaester, and the composition of the produced ester can be adjusted by the ratio of the raw materials used. The reaction mixture of sucrose and fatty acid ester thus obtained contains SE, DMSO as a reaction solvent, unreacted raw materials, an alkali catalyst and the like. The present invention seeks to recover SE from this mixture with high purity and high yield.

In the present invention, first, the reaction mixture is subjected to liquid-liquid extraction using an organic solvent azeotropic with water and water as an extractant, SE in the reaction mixture is extracted into an organic solvent phase, and DM is added.
SO and unreacted sucrose 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 part of the DMSO to adjust the concentration in advance. The DMSO is distilled off by using, for example, a thin film evaporator under reduced pressure at a temperature of 60 to 150 ° C.

Also, at the end of the reaction of sucrose and fatty acid alkyl ester, DMS is refluxed from the condenser to the reaction vessel.
It is also possible to adjust the concentration of DMSO in the reaction mixture to the above-mentioned range by extracting a part of O out of the system. The concentration of DMSO in the reaction mixture used for liquid-liquid extraction is preferably in the range of 10 to 80% by weight, particularly 20 to 50% by weight.

Since the alkaline catalyst remains in the reaction mixture, it is preferable to neutralize it before conducting liquid-liquid extraction. By adjusting the pH of the aqueous phase during liquid-liquid extraction, the hydrolysis of SE during extraction is suppressed, and efficient extraction of SE into the organic solvent phase and liquid separation between the organic solvent phase and the aqueous phase are achieved. It can be further improved. A suitable pH for liquid-liquid extraction is 3 to 7.0, especially 4 to 6.5. The adjustment of pH at the time of extraction may be carried out by adding an acid to the reaction mixture in advance, or may be carried out by mixing the reaction mixture with an aqueous acid solution and an organic solvent.

The organic solvent azeotropic with water used for the liquid-liquid extraction is an alcohol or ketone 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 or methyl isobutyl ketone are used, and among them, n-butanol and isobutanol are preferable. The amount of the organic solvent used in the reaction mixture is usually 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight, based on 1 part by weight of SE in the reaction mixture. On the other hand, the ratio of water used is usually 0.05% of water to 1 part by weight of the organic solvent.
10 to 10 parts by weight, preferably 0.5 to 2 parts by weight.

The acid used for pH adjustment is
Usually, it is an organic acid selected from formic acid, acetic acid, propionic acid, oxalic acid, succinic acid, 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 organic acid used is usually in the range of 0.1 to 3.0 equivalents based on the amount of the alkali catalyst used for the reaction of sucrose and fatty acid ester. From the viewpoint of suppressing SE hydrolysis during liquid-liquid extraction, migration of SE to the water phase side, and poor interface formation during extraction, it is 0.
The range of 5 to 1.5 is preferable.

The liquid-liquid extraction of the reaction mixture in the present invention is more preferably carried out in the presence of a salting-out agent for stable operation. The type of salting-out agent is optional, but the pH
The salt of the organic acid used for the adjustment is preferable. From the viewpoints of safety and stability as an additive for SE foods, pharmaceuticals, kitchen detergents, feeds and the like, and interface forming properties during extraction, alkali citrate or alkali lactic acid is preferable. Liquid-liquid 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 liquid-liquid extraction can be carried out using any known extractor such as a mixer-settler extractor, a countercurrent differential type extraction column, a non-stirring stage type extraction column, and a stirring stage type extraction column.
A mixer-settler type extractor is preferable in terms of economy, extraction efficiency and the like. The extraction is preferably performed in multiple stages. For example, the mixer-settler type extractor is used for the first stage extraction, and the obtained organic solvent solution containing SE is supplied to the lower part of the rotary disk type extraction column to raise it, and water is supplied from the top of the column to lower it. Then, DMSO in the organic solvent solution is extracted into the aqueous phase. An organic solvent solution containing almost no DMSO was recovered from the top of the column and fed to the next distillation step, and DMSO was collected from the bottom of the column.
The aqueous solution containing is recovered and supplied to the mixer-settler extractor of the first stage.

The recovery of SE from the organic solvent solution containing SE obtained by liquid-liquid extraction is carried out by azeotropic distillation from this SE-containing organic solvent solution to distill most of the organic solvent to obtain an aqueous solution of SE. To get A combination of a distillation step and a thin film evaporation step of recovering SE by distilling off the remaining organic solvent and water from this SE aqueous solution is performed. Even if the SE-containing organic solvent solution is heated under reduced pressure conditions to distill off the organic solvent without performing azeotropic distillation, it is difficult to distill the organic solvent sufficiently and it is difficult to obtain high-purity SE.

In order to obtain an SE aqueous solution by distilling off the organic solvent from the SE-containing organic solvent solution by azeotropic distillation, water is supplied from the lower part of the distillation column and the organic solvent solution is supplied from the upper part of the distillation column. Do. The organic solvent forms an azeotrope with water vapor rising from the lower part of the tower and is distilled off from the top of the tower, and an aqueous solution of SE having a reduced organic solvent concentration is recovered from the lower part of the tower.

The amount of water supplied to the distillation column is usually 0.1 to 10 times by weight, preferably 0.1 to 5 times by weight, the amount of the organic solvent solution to be supplied. A plate column and a packed column are usually used as the distillation column. S
A packed column is preferable from the viewpoint of foaming of E and economical efficiency. The SE aqueous solution obtained by the above-mentioned distillation step is then subjected to substantially complete removal of the organic solvent remaining in the thin film evaporation step to obtain SE. This step is performed using a thin film evaporator. As the thin film evaporator, usually, a rising thin film type, a falling thin film type, a horizontal thin film type, the above-mentioned various types and a type of rotating a rotary blade in a heating tube are used. Preferably, a thin film evaporator of a type in which a falling film type and a type of rotating a rotary blade in a heating tube are combined is used.

The number of treatments by the thin film evaporator is arbitrary, but normally, it is advantageous to use a device in which two or more thin film evaporators are connected in series and to perform a plurality of treatment processes. By doing so, the processing conditions can be adapted to the state of the aqueous solution. The treatment is preferably carried out under reduced pressure. Normally 40 under pressure of 1-100KPa
Process at ~ 150 ° C, but under pressure of 5-70 KPa
More preferably, the treatment is performed at 0 to 120 ° C. In this step, the organic solvent contained in the SE aqueous solution in a trace amount is substantially completely removed. If the amount of the organic solvent in the SE aqueous solution is large, it is preferable to add water to the SE aqueous solution and apply it to a thin film evaporator to accelerate the distillation of the organic solvent.

[0024]

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 Sucrose and DMSO were charged into a reactor and heated under reduced pressure to boil DMSO. A part of the steam was distilled out of the system to remove the water in the system, and when the water content of the liquid in the system reached about 0.06%, the distillation of the steam was stopped. Then, methyl palmitate and anhydrous potassium carbonate as a catalyst were added to the reactor, and the reaction was carried out at about 90 ° C. while boiling DMSO under reduced pressure. The molar ratio of methyl palmitate to sucrose is 0.
3. The molar ratio of potassium carbonate to palmitate was 0.008.

After completion of the reaction, an equal amount of lactic acid was added to the alkali catalyst to neutralize the catalyst. DMSO was then distilled off from the reaction mixture and concentrated to obtain a composition of DMSO 30%, unreacted sucrose 45.7%, SE 22.3% and other 2%.

Liquid-Liquid Extraction The above composition was subjected to liquid-liquid extraction using isobutyl alcohol and water. Isobutyl alcohol 60%, water 26
% And SE 14% isobutyl alcohol solution was recovered.

Isobutyl alcohol recovery To the packed column, the isobutyl alcohol solution obtained above was supplied from the upper part, and water was supplied from the lower part to 80 ° C., 5
Azeotropic distillation was performed under a pressure of 5.3 KPa. The supply ratio to the tower is 1.9 parts of isobutyl alcohol solution to 1 part of water.
It was 6 parts. From the top of the tower, isobutyl alcohol 61
% And 39% water distillate was collected. The recovery rate of isobutyl alcohol was 97.7%. The composition of the SE aqueous solution obtained from the lower part of the tower was 71.5% water, 25% SE, and 3.5% isobutyl alcohol.

Removal of Isobutyl Alcohol The SE aqueous solution obtained above was supplied to a vertical thin film evaporator together with water to remove isobutyl alcohol under the conditions of 100 ° C. and 10.7 KPa. The amount of SE aqueous solution supplied to the evaporator is 166.5 kg / hr per 1 m ^{2 of} heat transfer area.
And The amount of water supplied is 1 for 100 parts of SE aqueous solution.
It was 0.7 parts.

The water content of the SE aqueous solution flowing out from the thin film evaporator was 67%. Further, when the aqueous solution was analyzed by gas chromatography, the content of isobutyl alcohol was 50 ppm. This SE aqueous solution is again supplied to the vertical thin film evaporator at 126.1 kg / m ² , hr,
Isobutyl alcohol was removed under the conditions of 100 ° C. and 10.7 KPa. The composition of the solution flowing out from the evaporator was SE 51% and water 49%, and isobutyl alcohol was not detected by gas chromatography analysis using an FDP detector (the detection limit of gas chromatography was 20 ppm).

Dehydration of SE aqueous solution The SE aqueous solution obtained above was 58.3 kg / m ² , h
It is supplied to the horizontal thin film evaporator at 100 ° C and 10.7KPa.
Was treated under the following conditions. SE flowing out from the horizontal thin film evaporator
The water content was 0.62% by weight, and isobutyl alcohol and DMSO were not detected by gas chromatography analysis (DMS by gas chromatography).
The lower limit of O detection is 1 ppm).

Comparative Example 1 300 g of the isobutyl alcohol solution obtained by the liquid-liquid extraction of Example 1 was placed in a round-bottomed flask having an internal volume of 1 L for a rotary evaporator, and the pressure was increased for 2 hours at a temperature of 60 ° C. The pressure was reduced from atmospheric pressure to 1.3 KPa, then the temperature was raised to 90 ° C. over 2 hours, and the pressure was reduced to 0.67 KPa to remove isobutyl alcohol. On the way, foaming in the flask was severe, and the pressure was delicately adjusted to prevent the contents of the flask from flowing out. Then, the temperature was maintained at 90 ° C. and the pressure was 0.13 KPa for 2 hours, the temperature was cooled to room temperature, the contents were taken out, and the isobutyl alcohol concentration was measured by the same method as in Example 1 and found to be 250 ppm.

Comparative Example 2 After reaching a temperature of 90 ° C. and a pressure of 0.13 KPa in Comparative Example 1, once the pressure was brought to atmospheric pressure, 100 g of water was added, and the temperature was kept at 90 ° C. for 2 hours. The pressure was reduced from atmospheric pressure to 0.67 KPa. Foaming in the flask was as vigorous as in Comparative Example 1, and pressure control was performed to prevent outflow.
Next, the temperature was adjusted to 90 ° C. and 0.13 KPa, the temperature was held for 2 hours, the temperature was cooled to room temperature, the content was taken out, and the isobutyl alcohol concentration was measured by the same method as in Example 1 and found to be 110 ppm.

[0034]

According to the present invention, SE is obtained by the DMSO solvent method.
Is provided, and the obtained reaction mixture is subjected to liquid-liquid extraction, and SE is efficiently recovered from the organic solvent phase. By this method, high-purity SE extremely useful as an additive for foods, cosmetics, pharmaceuticals, etc.
Can be manufactured.

Claims (3)

[Claims] 1. A method for producing a sucrose fatty acid ester, which comprises reacting sucrose with a fatty acid alkyl ester using dimethyl sulfoxide as a reaction solvent in the presence of an alkali catalyst, wherein an alcohol or ketone having 4 or more carbon atoms that is azeotropic with water is used. The liquid-liquid extraction of the reaction mixture using the organic solvent and water as an extractant, the extraction step of extracting the sucrose fatty acid ester in the reaction mixture into the organic solvent phase and dimethyl sulfoxide and sucrose into the aqueous phase, the extraction step. The organic solvent solution containing the sucrose fatty acid ester obtained in 1. is supplied from the upper part of the distillation column, water is supplied from the lower part of the distillation column for distillation, and most of the organic solvent is distilled off to obtain an organic solvent concentration. Process to obtain a reduced sucrose fatty acid ester aqueous solution, which is fed to a thin film evaporator to evaporate water and to contain almost no organic solvent A method comprising performing each step of a thin film evaporation step of recovering sucrose fatty acid ester. 2. The method according to claim 1, wherein the thin film evaporator has a stirring blade therein. 3. The method according to claim 1, wherein the thin film evaporator is a vertical thin film evaporator.