JPH01299295A - Method for purifying sucrose ester of fatty acid - Google Patents

Abstract

PURPOSE:To industrially and readily obtain the subject compound without using a solvent, by regulating a reaction mixture containing a specific sucrose ester of a fatty acid to a neutral pH region, adding water, a neutral salt and sucrose thereto and washing the formed precipitates with acidic water. CONSTITUTION:Water is added to a reaction mixture containing an unreacted saccharide, unreacted fatty acid methyl ester, catalyst, soap, fatty acid and volatiles so as to provide 20:1 weight ratio of water:reaction mixture and pH is regulated to 6.2-8.2. A neutral salt and sucrose are added to the resultant mixture at ratios expressed by formula I (total amount of salt = amount of the added neutral salt + amount of salt by neutralizing the catalyst), formula II (total amount of saccharide = amount of added sucrose + amount of unreacted sucrose from the beginning) and formula III to afford precipitates, which are then collected by filtration, etc., and washed with acidic water regulated to pH3.0-5.5 and 10-40 deg.C temperature several times to provide the objective compound.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for purifying and isolating impure sucrose fatty acid esters on an industrial scale from a reaction mixture containing sucrose fatty acid esters when purifying sucrose fatty acid esters synthesized by a solvent method.

[Conventional technology]

BACKGROUND: Using water to form a molten mixture of sucrose with soap, i.e.
(without using a solvent), and reacted with higher fatty acid methyl ester in the presence of a catalyst (water-mediated SE synthesis; Japanese Patent Publication No. 51-1)
4485), there is no problem with residual solvent, but the reaction is carried out using a solvent such as dimethyl sulfoxide or dimethyl formamide (solvent method SE synthesis;
5-13102), the removal of the volatile matter remaining in the reaction mixture, that is, the residual reaction solvent, becomes an important problem.Recently, this volatile matter (hereinafter referred to as (reaction solvent)) For example, according to the regulations of the US FDA, the residual reaction solvent dityl sulfoxide in sucrose fatty acid ester (hereinafter also abbreviated as (sE)) is limited to 2 ppm or less (Fed, Registration). ,,51(214)
, 40160-1). (Problems with the prior art) Conventionally, SE generation reaction mixtures containing reaction solvents such as dimethyl sulfoxide and dimethyl formamide (in addition to SH, soaps, fatty acids, unreacted fatty acid methyl esters, unreacted sugars, catalysts, etc.) have been It required a complicated operation to remove it from the mixture (containing it). For example, according to the representative Japanese Patent Application Laid-Open No. 51-29417, a mixed solution of water and a purified solvent (especially called that to distinguish it from a reaction solvent) has a light liquid layer (upper layer) and a heavy liquid layer. In other words, since the heavy liquid layer (lower layer) generally contains a large amount of water, hydrophilic unreacted sugars, catalyst-derived salts, etc. On the other hand, since the light liquid layer (upper layer) contains a large amount of purified solvent, less polar substances such as SE, fatty acids, and unreacted fatty acid methyl esters are dissolved in this light liquid layer. However, reaction solvents such as dimethyl sulfoxide dissolve in the lower heavy liquid layer, but unfortunately they also dissolve in the upper light liquid layer, so this method cannot completely separate the reaction solvent. Therefore, a very large amount of purified solvent was required just for the purpose of removing a trace amount of the reaction solvent. However, the excessive use of purified solvent caused the following problems, which were: Regardless of the small-scale case, the disadvantages and inconveniences caused by this are noticeable in factories that manufacture SE on an industrial scale. ■ Risk of explosion and fire. ■ Preparation for the above ■ ■ Making the manufacturing equipment hermetically sealed in preparation for ■ above. ■ Making the entire building fireproof in preparation for ■ above. ■ Increased fixed costs due to ■, ■, and ■ above. ■ Increased cost due to solvent wear and tear. ■ Negative effect of residual solvent remaining in the product sucrose fatty acid ester. ■ Impact on employee health, which in turn increases the number of customers and increases costs. These circumstances Therefore, the development of a purification technique that eliminates the need for the use of purification solvents during SE purification has been a pressing need in the industry.

[Problem to be solved by the invention]

In the present invention, when purifying crude SH synthesized by a solvent method,
The objective is to solve all the problems caused by the use of solvents by developing a purification means that causes virtually no loss of SH, even though no purification solvent is used. C Means for Solving Problems] (Summary) In order to solve the above problems, 1. The method for producing sucrose fatty acid ester according to the present invention consists of unreacted sugar, unreacted fatty acid methyl ester, catalyst, The sucrose fatty acid ester-containing reaction mixture containing soap, fatty acids, and volatile components was heated to a neutral pH range.
The method is characterized in that the precipitate produced by adjusting the pH and adding water, a neutral salt, and sucrose is collected by filtration, and the precipitate is washed with acidic water. (Progress and Principle of the Invention) By the way, methods for precipitating SE in one reaction mixture and separating it from hydrophilic substances such as unreacted sugars without using a purifying solvent are well known. (1) SH precipitation method using acidic aqueous solution (British Patent No. 80
9,815 (11359)) (2) A method of precipitation of SE using a general neutral salt aqueous solution (Japanese Patent Publication No. 4.2-8850) is known. However, when an aqueous solution of hydrochloric acid is added to the reaction mixture as in method (1), SE is immediately precipitated, but unreacted sucrose is easily decomposed and converted into glucose and fructose, and even at low temperatures ( Even if the temperature is 0 to 5°C, decomposition cannot be avoided, making it difficult to recover and reuse unreacted sugar. Furthermore, even if an aqueous solution of a neutral salt such as common salt or Glauber's salt is added to the reaction mixture as in method (2), SE will immediately precipitate. In this case, unreacted sugars do not decompose, but the monoester, which is a useful component in SE, is dissolved in the aqueous phase, which not only causes a large loss but also increases the It becomes a hindrance when you want to get SE. Therefore, the inventors of the present invention aimed to (a) not only minimize the amount of SE dissolved in the aqueous phase side, but also precipitate the entire amount of SE by reducing the dose to zero if possible; and (+1) prevent the decomposition of unreacted sugars. As a result of conducting many salting-out experiments, we have conducted many salting-out experiments with the following three goals: (c) separating the residual reaction solvent from the SE by dissolving it outside the aqueous phase. The appropriate pH when the aqueous solutions of the two substances are dissolved in the reaction mixture. Under the combination of temperature, neutral salt concentration, sucrose concentration, and water amount, not only almost the entire amount of SE precipitates, but surprisingly, the aqueous phase contains reaction solvent in addition to unreacted sugar. We have discovered a convenient phenomenon that leads to dissolution. Therefore, by taking advantage of this phenomenon, by dissolving the precipitated SE in water and repeating the precipitation operation with a neutral salt and sucrose aqueous solution, the remaining volatile content can be effectively prevented while preventing the loss of SE. (
The remaining reaction solvent) can be completely transferred into the aqueous phase, and the neutral salt and sucrose accompanying the precipitated SE can be removed by washing the precipitate with acidic water of appropriate FH. It has been found that the SE can be substantially removed by the method, resulting in purified SE. The present invention is based on one or more novel findings. The details of the invention will be described below. (SE reaction mixture) In the synthesis of SE by the solvent method, 1. Usually, a mixture of sucrose and fatty acid methyl ester is added and dissolved in a reaction solvent 1, for example, dimethyl sulfoxide, in an amount several times the total amount of these, and carbonic acid is added. By holding the temperature at 80 to 90°C for several hours in a vacuum of 2° to 30 Torr in the presence of an alkaline catalyst such as potassium (K2CO3), the SE reaction mixture can be easily converted to a reaction rate of 90% or more (based on fatty acid methyl ester). is generated. Next, to quench the activity of the alkaline catalyst in the SE reaction mixture, an equivalent amount of an organic acid such as lactic acid, acetic acid, or a mineral acid such as 2ft hydrochloric acid is added to the SE reaction composition. This neutralization converts the catalyst into a potassium salt such as potassium lactate. Finally, one reaction solvent, such as dimethyl sulfoxide, is distilled off under vacuum, resulting in a composition (reaction mixture after neutralization and distillation) approximately having the following composition range. Sucrose fatty acid ester = 15-92% unreacted sugar
= 1.0-80% unreacted fatty acid methyl ester = 0.5-10% neutral salt of potassium carbonate
= 0.05-7% soap =1.
0-10% fatty acid = 0.5-10
% volatile content (residual reaction solvent) = 5.0 to 30% At this time, the ester distribution of SH is monoester 10% to 75%
% (diester or more is 90% to 25%), and the fatty acid roots mainly contained in each of fatty acid methyl esters, soaps and fatty acids are saturated and have a common CI of 6 to 25%.
It has a carbon number of C22. (Addition of water) Next, add water to the above reaction mixture. Water: Reaction mixture = 5:1 to 40:1 (weight ratio)...(1
), more preferably, water:reaction mixture = 20:1 (weight ratio)... (2) and the pH is adjusted to 8.2 to 8. 2. The pH is preferably 7.5. In this case, the water addition ratio is outside the above range. For example, if water/reaction mixture = 5, the viscosity of the resulting aqueous solution becomes so high that subsequent operations become virtually impossible. On the other hand, if an excess of water is added so that water/reaction mixture =>40, the viscosity decreases, making subsequent operations easier, and also making it easier to remove the desired reaction solvent. However, on the other hand, when recovering unreacted sugars and the like, a large amount of energy cost is required to remove water, resulting in a loss of economic efficiency. Furthermore, the pH of the aqueous solution is preferably adjusted between pH 6.2 and 8.2 in order to avoid decomposition of the target SE. There is a concern that decomposition of SH may occur.
Furthermore, even in the weakly acidic range of 6.2 or less, there is a risk of acid decomposition when exposed to high temperatures of 80° C. or higher, for example. (Salting out) To the aqueous solution of the SE reaction mixture whose pH was adjusted as described above,
Add more neutral salt and sucrose. In this case, it is preferable that the neutral salt to be added first satisfies the following formula (3). =0.015-0.12 (weight ratio)
3) Here, total base amount = amount of φ group to be added + scene formed from catalyst (4) Total amount of sugar = sucrose to be added + initial amount Amount of unreacted sugar from...
(5) Next, the amount of sucrose to be added is preferably determined by the following formula (6). = 0.025-0.201 quantitative ratio)...
-(6) Furthermore, in addition to both of the above formulas, it is preferable that the weight ratio of the total base amount and the total sugar amount also satisfy the following formula (7). The present inventors have developed S
When an aqueous solution containing a precipitate of E is heated to a temperature of 50 to 80 °C, even if the volatiles contained in the SE reaction mixture (
It has been found that approximately the entire amount of SE is precipitated even if the composition of the remaining reaction solvent varies widely from 5.0 to 30.0%. This phenomenon is a unique phenomenon and has important value for the purpose of the invention. The attached FIG. 1 is a ternary graph showing this phenomenon in more detail. In this figure, the weight of SH dissolved in the aqueous phase = Y [g]. Weight of precipitated SE = X [g] Weight ratio of SE dissolved in the aqueous phase to total SE (X + Y) [g] = φ [%], then φ is calculated using the following formula. Defined in (8). Here, the following conditions: Temperature: 80°C, pH = 7.5, Water: Reaction mixture = 14: l (weight ratio) Fatty acid residue = Stearic acid Composition of the reaction mixture Sucrose fatty acid ester = 29% Unreacted sugar = 35% Unreacted fatty acid methyl ester = 2% Salt derived from catalyst = 1% Soap = 3% Fatty acid = 1% Volatile content (residual reaction solvent) = 28% Ester distribution in SE: Monoester = 73% or more diester =27%, how the value of φ changes is shown by triangular coordinates. Here, 1 total salt is the amount defined by formula (4) and 1 total sugar is the amount defined by formula (5), respectively. Water + total salt and total sugar = 100. The shaded part in Figure 1 is the formula (3) discovered by the present inventors.
)1 is a region that simultaneously satisfies equations (6) and (7). By determining the amount of dissolved neutral salt and sucrose that falls within this shaded area, it is possible to substantially precipitate φ=0, that is, approximately the entire amount of SE, and filter the precipitated SE. Volatile matter dissolved in the water phase is removed by separation or centrifugation.
(residual reaction mixture) can be completely separated (that is, contaminating volatile components can be completely removed). (Washing) After the above salting-out operation, use acidic water whose pH is adjusted to 3.0 to 5.5 and the temperature is about 10"Q to 40°C. The above-mentioned separated SE cake is washed. The acids used for this purpose are, for example, mineral acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid and lactic acid, but are not limited to those exemplified in the side column.Such conditions The desired impurities can be transferred to the aqueous phase while minimizing the amount of SE redissolved from the cake side to the aqueous phase side. When the temperature exceeds 40°C, there is a concern that the SE will not only be decomposed by acid, but also that the viscosity will increase, making the operation difficult. In order to maintain a low temperature of 10°C or less, it is necessary to use a refrigerator that does not consider economic efficiency. Therefore, it is usually preferable to operate at a temperature of 10°C to 40°C, especially around room temperature. 1 When cleaning SE cake
It is necessary to remove from the SE cake as much as possible the volatile components (reaction solvent) contained in the main cake, unreacted sugars, added neutral salts, and salt surroundings produced by neutralization of the catalyst. Therefore, it is desirable that the SE cake be shredded in the acidic water to the smallest possible particle size.
Homo mixer)), homogenizer or colloid mill (
For example, this can be efficiently achieved using a fragmentation device such as the product name (Mycolloider). Migrate into the aqueous phase. However, although it is said to be a substantially small amount, it is inevitable that some SE will elute into the acidic aqueous phase. Therefore, it can be effectively suppressed by relatively increasing the diester or triester content. The above washing of the SE cake with acidic water becomes more complete by increasing the number of washings and increasing the amount of washing water, thus making it possible to obtain purified SE that is virtually pure.

【Example】

Hereinafter, the embodiments and effects of the invention will be explained in Examples and Comparative Examples, but the examples are of course for explanation and are not intended to limit or limit the idea of the invention. Example-1 After the reaction solvent was distilled off from the solvent method SE reaction mixture represented by the composition shown in Table-1 below, the residual liquid was neutralized with lactic acid, and then 2,000 g of water was added to 100 g of the dried substance to dissolve it. Ta. (Left below) Table 1: Distribution of esters: 70% monoester, 30% diester or higher. 92.5 g of sucrose and 97.8 g of 50% potassium lactate were added to the above aqueous solution, heated to 75° C., and the precipitated cake was collected by filtration. The composition of the solid obtained by drying this cake at 80° C. under vacuum was as shown in Table 2 below. Table 2 When the amount of SE in the filtrate remaining after filtering the cake was measured by gel filtration chromatography (see page 63 of Applicant Company Series (Sugar Ester Story)), no loss of SE was observed. Moreover, 85% of the reaction solvent (dimethyl sulfoxide) was removed. Next, 44 g of solid material having the composition shown in Table 2 above and 5 g of water were added.
When 2,000 g of room temperature mounded acid water with a pH of 3.5 was added to 100 g of a slurry consisting of 6 g of S.
Precipitation of H occurred. After this acidic aqueous solution containing the precipitate with a pH of 3.5 was homogenized using a homomixer (manufactured by Tokushu Kiki Kogyo ■), the i!
! The precipitate was filtrated, the pH was adjusted to 7.3, and the pH was adjusted to 8.
It was dried at 0°C. The composition of the obtained solid was as shown in Table 3 below. After distilling off the solvent from the solvent method SE reaction mixture represented by the composition shown in Table 1 above, 100 g of the dry matter was neutralized with lactic acid and
2,000 g of water was added and dissolved. To this aqueous solution, 28.5 g of sucrose and 65.6 g of 50% potassium lactic acid were added, and the temperature was raised to 75°C.
Thereafter, the same procedure as in Example 1 was carried out to obtain the solids listed in Table 4 below. Table 4 In addition, the amount of SE contained as a loss in the filtrate separated from the cake was determined by gel filtration chromatography (described above).
When quantitatively determined, the loss of SE was 0.02 g (only 0.06 of the initial amount, and 95% of the reaction solvent (dimethyl sulfoxide) was removed. 44g of solids and 56g of water
When 3,000 g of acetic acid-intoxicated water at room temperature was added to 100 g of a slurry consisting of p) 14.0, a white cloudy SE precipitate was immediately formed. This acidic aqueous solution containing the precipitate with a pH of 4.0 is uniformly divided using a homomixer, and then centrifuged to collect the precipitate.
After adjusting to H7.3, it was dried at 80° C. under vacuum. The composition of the obtained solid was as shown in Table 5 below. Table 5

【Effect of the invention】

As explained above, the present invention utilizes the unique solubility properties of sucrose fatty acid ester when purifying crude SH synthesized by a solvent method, resulting in a substantial loss of SH regardless of the use of a purifying solvent. By being able to provide a means for producing this ester without any esters, it has made a significant contribution to the industrial production of this ester.

[Brief explanation of the drawing]

FIG. 1 is a triangular graph showing the relationship between the respective maximum changes in water, total sugar, and total salt and the amount of sucrose fatty acid ester dissolved in the aqueous phase. Patent applicant No.-Kogyo Seiyaku Co., Ltd. 1 → 8' Salt (%)

Claims (1)

[Claims] 1. A sucrose fatty acid ester-containing reaction mixture containing unreacted sugar, unreacted fatty acid methyl ester, catalyst, soap, fatty acid, and volatile components is adjusted to a pH in the neutral range, and then mixed with water, The precipitate formed by adding salt and sucrose is collected by filtration,
A method for purifying sucrose fatty acid ester, which comprises washing the precipitate with acidic water. 2. The method according to claim 1, wherein the reaction mixture is adjusted to pH 6.2 to 8.2. 3. The method of claim 1, wherein water, neutral salts and sucrose are added to the reaction mixture maintained at 50-80C. 4. The method according to claim 1, wherein the weight ratio of water to reaction mixture to be added is water:reaction mixture = 5:1 to 40:1. 5. The method according to claim 1 or 3, wherein the neutral salt and sucrose are added to the reaction mixture according to the following relationship: Total salt amount/water amount + total salt amount + total sugar amount = 0.015 to 0
．． 12 and total sugar amount/water amount + total salt amount + total sugar amount = 0.025 to 0
．． 20 and total amount of salt/total amount of sugar = 0.4 to 0.6 where, total amount of salt = amount of neutral salt to be added + amount of salt produced by neutralization of catalyst Total amount of sugar = amount of SHORT to be added Amount of sugar + amount of unreacted sugar from the beginning 6, the acid used to adjust the pH of the reaction mixture is lactic acid,
2. The method according to claim 1, wherein the acid is any acid selected from the group consisting of acetic acid, hydrochloric acid and sulfuric acid. 7. The composition of the reaction mixture is: Sucrose fatty acid ester = 15-92% Unreacted sugar = 1.0-80% Unreacted fatty acid methyl ester = 0.5-10% Catalyst (K
_2CO_3) = 0.05~7% Soap = 1.0~
6. The method according to claim 1, wherein: 10% fatty acid = 0.5-10% volatile content (residual reaction solvent) = 5.0-30%. 8. Any one of claims 1 to 7, wherein the fatty acid radicals mainly contained in each of the fatty acid methyl ester, soap, and fatty acid in the reaction mixture are common saturated fatty acid radicals, and have a carbon number of 16 to 22. Method described. 9. The method according to claim 1, wherein the volatile component (residual reaction solvent) in the reaction mixture is dimethyl sulfoxide or dimethylformamide. 10. The method according to claim 1, 3 or 5, wherein the neutral salt to be added is any salt selected from the group consisting of common salt, mirabilite, potassium lactate and potassium acetate. 11. The ester distribution of sucrose fatty acid ester is 10% to 75% as monoester content (diester or more is 9%).
8. The method according to claim 1 or 7, wherein the amount is 0% to 25%). 12. The method according to claim 1, wherein the acidic water has a pH value of 3.0 to 5.5. 13. The method according to claim 1 or 12, wherein the temperature of the acidic water is 10°C to 40°C.