JPH04257598A - Production of sugar fatty acid ester - Google Patents

Abstract

PURPOSE:To efficiently obtain the subject compounds useful as an edible dispersant, etc., by reacting sugar with a lower alcohol ester of a fatty acid in the presence of an alkali in a specified solvent, then adding an organic solvent and water thereto for extraction separation of the reaction product, recovering unreacted substances from the aqueous phase and recycling them. CONSTITUTION:In production of a sugar fatty acid ester by a reaction of sugar with a lower alcohol ester of a fatty acid in the presence of an alkali in dimethylsulfoxide (DMSO) as the reaction solvent, the reacted mixture is mixed with an organic solvent and water and the organic solvent phase containing the sugar fatty acid ester is separated from the aqueous phase containing unreacted sugar, salts and dimethylsulfoxide. The organic solvent is removed from the organic solvent phase to separate the sugar fatty acid ester as the reaction product. The aqueous phase is treated with an ion-exchange resin to desalt and water is subsequently removed from the treated aqueous solution to recycle the resultant dimethylsulfoxide solution of unreacted sugar into next reaction system. Thus, the objective sugar fatty acid ester (SE) can be efficiently produced.

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 sucrose fatty acid ester (hereinafter abbreviated as SE). More specifically, the present invention combines SE, unreacted sucrose, solvent, inorganic salts and/or
Alternatively, it relates to a method for efficiently separating organic acid salts (hereinafter, these may be collectively abbreviated as salts).

0002

BACKGROUND OF THE INVENTION SE is a nonionic surfactant useful as an edible dispersant, emulsifier, detergent, etc. Conventionally, its production method involves a transesterification reaction between sucrose and a fatty acid ester such as fatty acid methyl in a solvent such as N,N-dimethylformamide or dimethyl sulfoxide (hereinafter abbreviated as DMSO) in the presence of an alkali catalyst. A method such as that described in Japanese Patent Publication No. 35-13102 is known.

The reaction mixture obtained by the above method is
In addition to SE, it contains a solvent, unreacted sucrose, and an alkali catalyst. To separate SE from this mixture,
Typically, an acid is added to the reaction mixture to neutralize and deactivate the catalyst, followed by partial distillation of the solvent, followed by extraction with an organic solvent such as hexane, butyl alcohol, methyl ethyl ketone, methyl isobutyl ketone, and water. The organic solvent is removed by distillation from the organic solvent phase containing mainly SE. A method for recovering SE has been proposed. (For example, Tokuko Sho 48-21927, Tokuko Sho 48-350
49, Japanese Patent Publication No. 50-29417, Japanese Patent Application Publication No. 50-1307
12) It is important as an industrial production method and an economical operation method that the unreacted sucrose and reaction solvent recovered in the aqueous phase are used again as SE production raw materials after removing water by distillation. However, in the extraction process using an organic solvent and water, it is necessary to add a salting-out agent such as an organic acid salt in order to obtain good liquid separation (Japanese Patent Application Laid-Open No.
0-130712), as a result there is salt accumulation in the sucrose recovered in the aqueous phase. If water is removed by distillation and the recovered sucrose is directly used as a raw material for SE production, the rate of transesterification reaction is delayed due to the influence of accumulated salts, and this method poses problems for economical operation. .

[0004] As a means to partially solve the above problems, after removing DMSO from the reaction mixture, a precipitation solvent that dissolves SE but does not dissolve sucrose is added, and unreacted sucrose is precipitated and recovered. A method has been proposed. For example, JP 63-27497 and USP 3,251,
No. 829 describes an invention in which methyl ethyl ketone is used as a precipitation solvent. Also, JP-A-2-1529
86 describes an example of methyl isobutyl ketone. However, in the above method, a total amount of salt is precipitated along with sucrose, and since there is still no means to remove the salt from the recovered sucrose, as a result, accumulation of salt in the recovered sucrose is unavoidable. From a concentrated reaction mixture with a large accumulation of salts,
Even if a ketone is mixed to recover unreacted sucrose, the sucrose remains in a paste state and does not precipitate, so this method has problems as an industrial production method. In addition, in this method, since sucrose is precipitated as a solid, solid-liquid separation steps such as centrifugation and compression are essential, and continuous operation is difficult compared to methods using only a liquid system. This point also poses a problem as an industrial manufacturing method.

[0005]

Problems to be Solved by the Invention The present invention aims to recover sucrose without salt accumulation from the SE production reaction mixture and to recover it from the SE production reaction mixture.
The object of the present invention is to provide an industrial manufacturing method for use as a manufacturing raw material and an economical operating method that allows easy continuous operation.

[0006]

[Means for Solving the Problems] As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the aqueous phase separated by the conventional method using an organic solvent and water is treated with an ion exchange resin. This objective was achieved by separating and removing the salts and reusing the unreacted sucrose DMSO solution free of salt contamination in the next reaction system. That is, the present invention provides a method for producing sucrose fatty acid ester by reacting sucrose and fatty acid lower alcohol ester in the presence of an alkali using dimethyl sulfoxide as a reaction solvent,
■ The reaction mixture is mixed with an organic solvent and water, and then separated into an organic solvent phase containing sucrose fatty acid ester and an aqueous phase containing unreacted sucrose, salt, and dimethyl sulfoxide, and ■ the organic solvent phase obtained in ■ The organic solvent is removed from the sucrose fatty acid ester, the aqueous phase obtained in step 2 is treated with an ion exchange resin, the water is removed from the aqueous solution obtained in step 2, and the unreacted phase obtained in step 2 is recovered. This is a method for producing sucrose fatty acid ester, characterized in that the sugar dimethyl sulfoxide solution is reused in the next reaction system.

The fatty acid lower alcohol ester in the present invention has 6 to 30 carbon atoms, preferably 12 to 22 carbon atoms.
saturated or unsaturated fatty acids such as caproic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid; linoleic acid,
Examples include esters of unsaturated fatty acids such as oleic acid, linoleic acid, erucic acid, and ricinoleic acid) and lower alcohols having 1 to 6 carbon atoms (for example, methanol, ethanol, propanol, butanol, etc.). Such lower alcohol esters may be used as a mixture of two or more. The fatty acid lower alcohol ester is usually 0.1 to 20 mol, preferably 0.2 to 20 mol, per 1 mol of sucrose.
Use 8 moles.

DMSO is used as the reaction solvent in the present invention from the viewpoints of thermal stability, solubility in sucrose, and safety. The amount of solvent used is based on the total amount of sucrose and fatty acid lower alcohol ester.
Usually 20-150% by weight, preferably 50-80% by weight
It is. As the alkali catalyst in the present invention, alkali metal hydrides, alkali metal hydroxides, alkali metal salts of weak acids, and the like are effective, and alkali metal carbonates (eg, potassium carbonate) are particularly preferred.

[0009] Acids used to neutralize and deactivate the catalyst in the present invention include inorganic acids such as nitric acid, sulfuric acid, hydrochloric acid, and phosphoric acid, formic acid, acetic acid, propionic acid, oxalic acid, succinic acid, benzoic acid, and citric acid. , lactic acid, and organic acids such as higher fatty acids having 8 to 22 carbon atoms. Among these, citric acid or lactic acid is particularly preferred from the viewpoint of corrosivity to equipment materials, solubility in water, and safety as a food additive.

In the present invention, an organic solvent and water are mixed with the reaction mixture after the transesterification reaction, and liquid-liquid extraction is performed. Here, although not necessarily essential, it is preferable to concentrate and remove DMSO from the reaction mixture before liquid-liquid extraction from the viewpoint of reducing the amount of organic solvent and water required for extraction. The removal of DMSO is usually carried out at a concentration of DMSO in the reaction mixture of 5 to 60% by weight, preferably 10 to 50% by weight.
All you have to do is concentrate and remove it. If too much DMSO is removed, the viscosity of the concentrated mixture increases, making it inconvenient for subsequent handling.

[0011] The liquid-liquid extraction in the present invention can be performed using a column-type countercurrent contactor that utilizes the difference in specific gravity between two phases, or a method that applies mechanical stirring or pulsation to this, as well as a method that uses centrifugal force to perform mixing. The separation method is selected from countercurrent methods such as the Potvilnyak centrifugal extractor, and cocurrent methods such as orifice towers and ejectors. Usually, a countercurrent method is employed, and a countercurrent multistage extraction method is preferred as an industrial method in terms of distribution efficiency and water usage.

The organic solvent used in the liquid-liquid extraction of the reaction mixture in the present invention is usually hexane, n-butanol, isobutanol, methyl ethyl ketone, methyl isobutyl ketone, etc., and preferably n-butanol, isobutanol, etc. can be mentioned. Although it is not necessary to add a salting-out agent in liquid-liquid extraction, it is preferable to add it for stable operation. The salting-out agent to be added is preferably the same type as that produced when the catalyst is neutralized and deactivated, and citrate or lactate is preferred from the viewpoint of stability as a food additive and interface formation during extraction.

The liquid-liquid extraction operation temperature in the present invention is usually carried out below the boiling point of the organic solvent at atmospheric pressure, preferably 40 to 80°C. The amount of the organic solvent used is usually 0.5 to 20 parts by weight, preferably 1 to 10 parts by weight, per 1 part by weight of SE in the reaction mixture. The ratio of organic solvent and water used is usually 1 part by weight of organic solvent to 0 part by weight of water.
．． 05 to 10 parts by weight, preferably 0.2 to 2 parts by weight.

[0014] From the organic solvent phase obtained by liquid-liquid extraction in the present invention, the organic solvent is removed to recover SE. Although the SE thus obtained can be used as is for general use, it is preferable to further refine it for use as a food additive. That is, it is preferable to remove trace amounts of organic solvents by steam treatment. Purified SE can be produced by concentrating and drying the water-containing crude SE after steam treatment.

[0015] The aqueous phase after liquid-liquid extraction in the present invention contains unreacted sucrose, DMSO and salt. Salt is further removed from this aqueous phase, and the process moves on to a step of separating and collecting unreacted sucrose DMSO solution. In the present invention, salts are removed by treating the aqueous phase with an ion exchange resin. The aqueous phase containing the salts is treated with a basic anion exchange resin to convert and adsorb the salts to the corresponding acids. Since the discharged liquid contains alkali in addition to unreacted sucrose and DMSO, it is then treated with an acidic cation exchange resin to adsorb and remove the alkali. The thus obtained effluent becomes an aqueous solution containing unreacted sucrose and DMSO, which is free of salt and alkali. If the alkali remains, it will react with the fatty acid alcohol ester to form soap and inhibit the reaction when it is reused in the next reaction system, so it is necessary to remove the alkali using a cation exchange resin. In addition, in removing salts, the processing order using anion exchange resin and cation exchange resin is as follows:
From the viewpoint of stability of sucrose, it is preferable to first perform treatment with an anion exchange resin to remove the acid.

[0016] Furthermore, in order to more completely purify the recovered sucrose DMSO solution, a decoloring treatment using a decolorizing agent can be carried out before or after this ion exchange resin treatment step. For example, an ion exchange resin for removing salt can be used in succession with an ion exchange resin for decolorizing sucrose. Strongly basic anion exchange resins and their Cl type resins are known for decolorizing sucrose. In addition to ion exchange resins,
Diatomaceous earth, acid clay, silica gel, activated carbon, etc. are used. If there is a possibility that the decolorizing agent may cause harmful contamination in the subsequent reaction system, the decoloring treatment is preferably carried out before the ion exchange treatment for removing salts.

Ion exchange resins used in the present invention include those having various chemical and physical structures. As for its physical structure, either gel type or porous type resin can be used. Further, a wide range of degrees of crosslinking can be applied. Representative examples of preferred ion exchange resins include those shown below, but the resins used in the present invention are not limited to these.

Anion exchange resin; a three-dimensionally polycondensed polymer base with a quaternary ammonium group or a
It is a resin bound with tertiary amine, and examples of specific products include Diaion SA and P manufactured by Mitsubishi Chemical Corporation.
Examples include the A and WA series. In the present invention, the PA series, which is a porous styrene-based strongly basic anion exchange resin, is preferable in terms of exchange rate, decolorization property, regeneration efficiency, etc. Cation exchange resin: A resin in which sulfonic acid groups, carboxylic acid groups, etc. are bonded as exchange groups to a three-dimensionally polycondensed polymer base. Specific products include, for example, Diamond manufactured by Mitsubishi Chemical Corporation. Examples include Aeon SK, PK, and WK series. In the present invention, the WK series, which is a weakly acidic cation exchange resin such as methacrylic or acrylic resin, is preferable in terms of sucrose stability, exchange rate, regeneration efficiency, etc.

The salt concentration in the aqueous solution during treatment with the ion exchange resin in the present invention is usually 0.1 to 50% by weight, preferably 1 to 30% by weight. The ion exchange resin treatment temperature in the present invention is usually 5 to 100°C, preferably 20 to 100°C.
The temperature is 70°C. The processing rate of the ion exchange resin in the present invention is usually 0.1 to 60 milliquivalents, preferably 1 to 30 milliequivalents, per liter of resin per hour as a salt supply rate.

Next, in the present invention, water is further removed from the aqueous solution containing unreacted sucrose and DMSO after removing the salt. If the water is reused in the next reaction system without being removed, the water and catalyst will react to produce potassium hydroxide, which will inhibit the reaction, so it is necessary to remove the water before mixing with the catalyst. In order to remove water from an aqueous solution, from the viewpoint of stability of sucrose, it is preferable to distill it off under reduced pressure, and the concentration of water is usually 10% by weight or less, preferably 1% by weight in the unreacted sucrose DMSO solution. % or less.

[0021] Also, unreacted sucrose and D after salt removal
If there is any residual organic solvent in the aqueous solution containing MSO, it is preferable to remove this as well. Distillation is carried out under reduced pressure in the same manner as in the case of water, and the concentration of the organic solvent is equal to that of unreacted sucrose DM.
In SO solution, usually 10% by weight or less, preferably 1% by weight
The following shall apply. The unreacted sucrose DMSO solution from which water and organic solvent have been removed in this manner is usually mixed with fresh sucrose and reused in the next reaction system. The unreacted sucrose DMSO solution obtained by the method of the present invention does not contain salt, and even if it is repeatedly reused in the next reaction system, the transesterification reaction will not be delayed.

[0022]

[Examples] The present invention will be described in detail below with reference to Examples, but the present invention is not limited by these Examples unless the gist thereof is exceeded. Reference example [Conventional method/Using new sucrose] Reaction/concentration process 3743 g of sucrose in a sufficiently dried 30 liter reactor equipped with a stirrer and 11 DMSO as a solvent.
．． 5 kg, boil the solvent under a pressure of 20 mmHg, cool the solvent vapor to condense and reflux, and
After 0 minutes, part of the solvent was distilled off to dehydrate the system. DMS
When the distilled amount of O reached 1 kg, the distillation was stopped and the water content of the system liquid was measured, and the water content was 0.06% by weight.

Next, 12 g of anhydrous potassium carbonate,
529.9 g of methyl palmitate and 227.1 g of methyl stearate were added, and while boiling DMSO at 20 mmHg, the vapor was cooled, condensed and refluxed, and the methanol produced was distilled out of the reaction system. Made it react. The reaction temperature was an average of 90°C, and the time required to reach 99% conversion of fatty acid methyl was 2.8 hours. The reaction was carried out for 3 hours.

After the reaction was completed, 32 g of a 50% aqueous solution of lactic acid was added to deactivate the catalyst. When the reaction mixture was analyzed by gel permeation chromatography, the SE composition was 80.7% monoester, 17.0% diester,
It was found that the triester content was 2.3% (area percentage), and the conversion rate of fatty acid methyl calculated from the remaining amounts of methyl palmitate and methyl stearate analyzed by gas chromatography was 99.6%. The composition of the reaction mixture taken out from the reactor was 19.5% of unreacted sucrose.
9% by weight, SE9.7% by weight, salt 0.15% by weight, DM
The SO content was 70.2% by weight.

15 kg of reaction mixture taken out from the reactor
A horizontal thin film evaporator (heat transfer area 0.1 m2, manufactured by Hitachi, Ltd.) was used, and the steam temperature in the heating part was 110°C.
When the liquid was passed under the condition of a pressure of 10 mmHg and a supply rate of 7 kg/Hr, the amount of liquid discharged was 5.4 kg. As a result of compositional analysis of the concentrated reaction mixture, sucrose was 49.5% by weight;
SE24.1% by weight, salt 0.4% by weight, DMSO26.
It was 0% by weight. Liquid-liquid extraction process The above concentrated reaction mixture was extracted with 10% aqueous isobutanol 15
．． It was dissolved in 5 kg. Next, add 15.5 kg of pure water to mix the unreacted sucrose and DMS in the SE-isobutanol solution.
O was extracted into the aqueous phase using a 2 liter separatory funnel repeatedly. Further, pure water containing 1500 ppm of potassium lactate was added to the SE-isobutanol solution to recover trace amounts of unreacted sucrose and DMSO. After removing water from the aqueous phase using a flash evaporator, unreacted sucrose-D
The MSO solution was collected. The salt concentration in the recovered unreacted sucrose was 1.8% by weight.

Comparative Examples 1 to 4 [Repeated reactions by conventional method] Unreacted sucrose (2000 g) recovered from the aqueous phase in the reference example
) - Reusing the DMSO solution, adding 1743 g of new sucrose to make sucrose raw material, and making the raw material preparation composition similar to the reference example, reaction, concentration, liquid-liquid extraction, sucrose-D
Recovery of the MSO solution and reuse with addition of fresh sucrose were repeated four times to produce SE, and the time required to reach 99% fatty acid methyl conversion was measured. The results are shown in Table 1 below.

Example 1 [Recovery of unreacted sucrose, removal of salt] The salt concentration in sucrose after the liquid-liquid extraction step of the first repeated reaction of comparative example (comparative example 1) was 3.0 weight Aqueous phase side solution containing % of unreacted sucrose (6.9% by weight of unreacted sucrose, 0.2% by weight of salt, 3.6% by weight of DMSO, 80.2% by weight of water, 9.1% by weight of alcohol) was treated with ion exchange resin. The ion exchange resin was packed in three jacketed glass columns with an inner diameter of 5 cm and a height of 80 cm.
Type) Ion exchange resin PA308, alkaline type (OH type)
800 ml each of ion exchange resin PA308 and acid type (COOH type) ion exchange resin TWK100 (both manufactured by Mitsubishi Kasei Corporation) were filled and maintained at 40°C. The aqueous phase solution was passed through the three resin-packed towers in sequence at a rate of 2.4 liters/hour. The color of the solution discharged from the TWK100 packed tower is slightly yellow, and the salt removal rate is 95%.
Met. A rotary evaporator is used to recover water and alcohol from the aqueous solution discharged from TWK100.
5.7% by weight, 34.2% by weight of DMSO, and 0.1% by weight of salt). The salt concentration in the recovered sucrose was 0.2% by weight.

Example 2 [Recovery of unreacted sucrose, removal of salt] The salt concentration of sucrose after the liquid-liquid extraction step of the fourth repeated reaction of the comparative example (comparative example 4) was 7.2% by weight. Aqueous phase side solution containing unreacted sucrose (6.9% by weight of unreacted sucrose, 0 salt)
．． 5% by weight, DMSO 3.6% by weight, water 79.9% by weight
, alcohol 9.1% by weight) was used.
The sample was treated with ion exchange resin in the same manner as above. TWK100
The color tone of the solution discharged from the packed column was slightly yellow, and the salt removal rate was 93%. A recovered sucrose-DMSO solution (65.5% by weight of unreacted sucrose, 34.1% by weight of DMSO, 0.4% by weight of salt) was obtained by recovering water and alcohol from the aqueous solution discharged from TWK100 using a rotary evaporator. Ta. The salt concentration in recovered sucrose is 0.6
% by weight. As can be seen from Examples 1 and 2, by using the ion exchange resin treatment of the method of the present invention, it is possible to separate and recover unreacted sucrose at a high concentration with extremely little salt accumulation from the reaction mixture.

Examples 3 to 6 [Repeated reactions according to the steps of the method of the present invention] Unreacted sucrose (2000 g) recovered in Example 2 - DM
The SO solution was reused and 1743 g of fresh sucrose was added to obtain a sucrose raw material. Using the sucrose raw material, reaction, concentration, liquid-liquid extraction, removal of salts by ion exchange treatment, and recovery of unreacted sucrose-DMSO solution were performed with the same raw material preparation composition as in the reference example. . Following this,
Reuse with fresh sucrose was repeated a total of 4 times to produce SE, and the time required to reach 99% fatty acid methyl conversion was measured for each. The results are shown in Table 2 below.

As can be seen from Examples 3 to 6, Comparative Examples 1 to 6
4, the method of the present invention suppresses salt accumulation even when unreacted recovered sucrose is repeatedly reused, and takes almost the same amount of time to reach 99% fatty acid methyl conversion rate as when fresh sucrose is used. can get.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Effects of the Invention] According to the method of the present invention, highly pure unreacted sucrose is separated and recovered from the reaction mixture, reused in the reaction, and repeatedly used to economically and efficiently produce sucrose and fatty acids. Esters can be produced and reused without slowing the transesterification reaction. In addition, since sucrose is recovered in a liquid system, continuous operation is easy and it is an industrially excellent method.

[Brief explanation of the drawing]

FIG. 1 is a simple flow diagram illustrating an example of the process of the present invention.

Claims (2)

[Claims] Claim 1. A method for producing sucrose fatty acid ester by reacting sucrose with fatty acid lower alcohol ester in the presence of an alkali using dimethyl sulfoxide as a reaction solvent, comprising: (1) mixing the reaction mixture with an organic solvent and water; Next, the organic solvent phase containing the sucrose fatty acid ester and the aqueous phase containing unreacted sucrose, salt, and dimethyl sulfoxide are separated, and the organic solvent is removed from the organic solvent phase obtained in step 2 to remove the sucrose fatty acid ester. Collect and ■
The aqueous phase obtained in step (2) is treated with an ion exchange resin, water is removed from the aqueous solution obtained in step (2), and the unreacted sucrose dimethyl sulfoxide solution obtained in step (2) is reused in the next reaction system. A method for producing a sucrose fatty acid ester. Claim 2: In the ion exchange resin treatment of the aqueous phase,
■ By treating the aqueous solution obtained as the aqueous phase with an anion exchange resin, the acid corresponding to the salt is adsorbed and removed, and ■ By treating the aqueous solution obtained in ■ with a cation exchange resin, the alkali is removed. 2. The manufacturing method according to claim 1, wherein the aqueous solution containing unreacted sucrose and dimethyl sulfoxide is recovered by adsorption and removal.