JPS5917120B2 - Method for producing sucrose ester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing sucrose ester, and more particularly to a method for producing sucrose ester, and more specifically, a method for producing a sucrose ester and a molten product consisting of sucrose and potassium or/and sodium carbonate (hereinafter referred to as alkali carbonate). The present invention relates to a method for producing a sucrose ester, which comprises heating a chain fatty acid ester to carry out a transesterification reaction.

Sucrose long-chain fatty acid esters are useful as nontoxic and microbially degradable surfactants, and are expected to have a wide range of uses such as food additives, cosmetic base materials, and detergents.

The present invention provides a novel and excellent method for producing sucrose esters. 5. As a method for producing long-chain fatty acid esters of sucrose, known esterification reactions, namely,
Applications include direct esterification reaction between sucrose and acid, reaction between sucrose and acid/lard, reaction between sucrose and acid anhydride, and transesterification reaction between sucrose and acid ester.
However, at present, only the transesterification method is used.

There are several patents and documents featuring the conditions of the transesterification reaction. The methods for producing these sucrose fatty acid esters are classified into the following three types.

The first method is called the solvent method or DMF method, in which an alkali catalyst is used in a solvent such as dimethylformamide or dimethyl sulfoxide, which is a common solvent for both sucrose and long-chain fatty acid ester. This is a method of reacting in the presence of
It is described in No. 02.

The second method is also called the half-solvent method or microemulsion method, in which sucrose and long-chain fatty acid 95 fatty acid ester are mixed with propylene glycol or water, which is a solvent for sucrose, and a large amount of alkali metal soap, which is an emulsifier. In this method, a transparent microemulsion is formed by mixing the two, and transesterification is carried out under heating.

Details of the microemulsion method can be found, for example, in Japanese Patent Publication No. 45-
No. 23534. The third method is the direct method or hot-melt method, in which sucrose and long-chain fatty acid ester are heated to a temperature close to the melting point of sucrose (1840-185°C) in the presence of a large amount of metal soap. This method involves heating at a high temperature for a short period of time.

Details of this method are described, for example, in Journal of the American Oil Chemist Society, Vol. 47, pp. 56-60. In the first method, the solvent used is relatively toxic, such as dimethylformamide or dimethyl sulfoxide, and it is difficult to completely remove it from the product. It is said that there are some difficulties when using it for food additives, cosmetic base materials, and other applications. The second method mentioned above is attracting attention as the most effective method for producing sucrose ester, but in this case too, the amount of solvent and at least 10% of the raw material sucrose and long chain fatty acid ester is several times that of the sucrose and long chain fatty acid ester.
It is necessary to use the above metal soap (preferably about 30% according to the examples in the specification of Japanese Patent Publication No. 45-23534). The disadvantages are the large size of the product, the complexity of the reaction operation, and the difficulty in purification, especially in removing a large amount of soap from the product.

The third method above can be said to be superior in that it does not use a solvent, but it requires the use of a similar amount of alkali metal soap as an emulsifier and catalyst as the second method, and requires a high-temperature reaction. Therefore, there are many side reactions,
It is said that there are problems such as large differences in reactivity depending on the type of fatty acid.

In the present invention, the long chain fatty acid that is a component of the long chain fatty acid ester used as a raw material has a carbon number of 8 to 22.
saturated and unsaturated fatty acids such as myristic acid, palmitic acid, stearic acid, behanic acid,
Examples include oleic acid, linoleic acid, linolenic acid, and ricinoleic acid, but mixtures thereof may also be used.

The method of the present invention is particularly suitable when the fatty acid component is a straight chain saturated fatty acid having 12 to 18 carbon atoms. On the other hand,
Alcohols that are constituents of long-chain fatty acid esters include lower alkanols such as methyl alcohol and ethyl alcohol, glycol monoalkyl ethers such as ethylene glycol monomethyl ether and propylene glycol monomethyl ether, and glycols such as ethylene glycol and propylene glycol. and glycerol.

When the alcohol is a polyhydric alcohol, it may be a monoester or a polyester. Of course, it is also possible to use mixtures of various fatty acid esters. A feature of the present invention is that a melt of sucrose and an alkali carbonate is used in the esterification reaction of sucrose.

Sucrose is highly crystalline, and it is virtually impossible to melt it in a solvent-free state without decomposition, and the solvents suitable for the esterification reaction are also limited to specific ones. This can be said to be a major factor inhibiting the esterification reaction of sucrose. The present invention relates to a new and excellent method for esterifying sucrose, which is different from the known methods for esterifying sucrose as described above. In other words, sucrose and an appropriate amount of potassium carbonate or sodium carbonate form a molten substance, which exhibits viscosity even below the melting point (decomposition point) of sucrose at temperatures above 100°C, and sucrose even at room temperature. Does not produce crystals. The inventors have discovered that when such a melt and a long-chain fatty acid ester are mixed and heated, the transesterification reaction easily proceeds.
In the method of the present invention, it is thought that the fact that sucrose is amorphous due to the presence of carbonate greatly contributes to the progress of this reaction. The preferred reaction temperature varies depending on the type of long chain fatty acid ester used, but is approximately 140°C.
to 180°C. The amount of carbonate required to form such a melt is 0 per mole of sucrose.
．． The amount of carbonate is 2 mol or more, and particularly suitable in the method of the present invention is in the range of 0.3 mol or more and 1.0 mol or less per 1 mol of sucrose.

Potassium carbonate and sodium carbonate may be used in combination, but the use of potassium carbonate gives better results in the progress of the reaction of the present invention. On the other hand, lithium carbonate and polyvalent metal carbonates do not form sucrose and a melt as described above. The melt of the present invention can be conveniently obtained by heating a predetermined amount of sucrose and carbonate together with a small amount of a suitable solvent such as glycol and evaporating the solvent while stirring.

When obtaining the melt of the present invention by such a method, potassium and sodium bicarbonates can be used as well as carbonates.
The ratio of the amounts of sucrose and long chain fatty acid ester used in the reaction is not particularly limited, but is preferably 0 to 1 mole of sucrose.
．． Preferably, 5 to 4 moles of fatty acid ester are used.

The transesterification reaction according to the method of the present invention is carried out while the alcohol constituting the long-chain fatty acid ester, which is one of the raw materials, is removed from the reaction system, as in the usual transesterification reaction.

Although reduced pressure operation is possible as a method for removing the produced alcohol from the reaction system, the purpose can also be achieved by slowly flowing an inert gas such as nitrogen or carbon dioxide through the reaction system. In the method of the present invention, it may be effective to add an alkali metal soap as a catalyst to the reaction system.

The appropriate amount of metal soap in this case is around 1% of the reaction system; if too large is used, the viscosity of the reaction system will increase, making the stirring operation difficult, and at the same time it will take a lot of effort to remove these soaps from the product. This is not preferable because it requires a lot of effort. This point can be said to be extremely small compared to the amount of metal soap used in the synthesis of sucrose esters by the microemulsion method or hot melt method described above, which is several tens of percent. In the present invention, the favorable effect produced by the addition of metal soap is thought to be due to the soap acting as a catalyst. The reaction mixture obtained by the method of the present invention is usually solid at room temperature and does not dissolve as it is in organic solvents that dissolve sucrose esters, such as hot acetone, hot methyl ethyl ketone, dimethyl formamide, and the like.

Although the reason for this is not entirely clear, it is thought that a melt of the produced sucrose ester and alkali carbonate is formed. The sucrose ester is liberated only by treating the reaction mixture with an aqueous acid solution to decompose the alkali carbonate. The reaction product dissolves quickly in water, but if left in this state, the ester bond of the sucrose ester will be rapidly hydrolyzed, so to avoid this, the product is dissolved in an aqueous solution that is kept acidic in advance. It is desirable to neutralize it by Moreover, the glycosidic bonds of sucrose esters are gradually hydrolyzed in acidic conditions, so it is necessary to avoid using too much acid with respect to the alkali carbonate in the product, and the pH after neutralization should be 3 or less. It is not desirable to become. Further, it is desirable that the neutralization operation and the subsequent separation operation of the sucrose ester be carried out quickly.
The type of acid used for the neutralization operation is not particularly limited, and various inorganic and organic acids can be used. It is also possible to use buffer solutions. A portion of the sucrose ester liberated by the neutralization treatment dissolves in water, and the rest forms a precipitate. The precipitate may be collected by mouth filtration, and the portion dissolved in water may be extracted and separated with a suitable organic solvent, or both may be extracted simultaneously. Extraction solvents include acetone, ketones such as methyl 5-ethyl ketone, esters such as ethyl acetate, and are not particularly limited. Depending on the purpose, it is also possible to use the reaction product without separating the sucrose ester after neutralization. One of the features of the present invention is that, unlike known methods for synthesizing sucrose esters, no solvent or emulsifier is used, which is advantageous in terms of reaction operation and cost.

That is, there is no concern about toxicity, which is a disadvantage of the solvent method, and the equipment can be simplified. Further, since a large amount of emulsifier is not used as in the microemulsion method or the hot melt method, separation and purification of the emulsifier is not necessary. The carbonate used in the present invention is inexpensive and easy to handle. This is an advantageous condition for reducing product costs.
One of the features of the present invention is that when appropriate reaction conditions are selected, extremely high reaction yields can be achieved among this type of reaction.

This will be clear from the examples described below. One of the features of the present invention is that the reaction between triglyceride or glycol diester and sucrose proceeds extremely easily.

Among the fatty acid esters used in the synthesis of known sucrose esters, fatty acid methyl esters are the most common, and the reality is that they are exclusively used industrially. However, the method of the present invention can use triglycerides, especially hydrogenated oils such as beef tallow and perilla oil, as one of the raw materials, fatty acid esters, and can achieve high yields, so it can be said that the industrial value is extremely large. . Example 1 5.2 f (0.015 mol) of sucrose and 1.07 (0.0075 mol) of anhydrous potassium carbonate were placed in a 100CC three-necked flask equipped with a motor stirrer, and 5.2 ml of water was added to mix both substances. It was dissolved and immersed in an oil bath that had been adjusted to a constant temperature of 150°C.

Nitrogen gas was passed through one end of the Mitsuro flask, and a condenser was attached to the other end. Water was removed while stirring, and a melt of sucrose and alkali carbonate began to form in several tens of minutes.

To this was added 4.57 (0.015 mol) of methyl stearate, and the reaction was continued at 150° C. for 3 hours while stirring again. The reaction mixture was a homogeneous dark brown paste;
When cooled to room temperature, it became solid. This product was treated with an aqueous solution containing about 2y of acetic acid to decompose the alkali carbonate.
The pH at this time was 4.0. The liberated sucrose fatty acid ester was extracted three times with about 100 ml of hot ethyl acetate.
This ethyl acetate layer was dried over anhydrous sodium sulfate, concentrated to about 10 volumes, and cooled to room temperature to obtain a precipitate. The precipitate was collected by filtration and dried to obtain 3.67 sucrose fatty acid ester as a white powder. Example 2 5.27 y (0.015 mol) of sucrose and 1.0 y (0.0075 mol) of anhydrous potassium carbonate were placed in a Mitsuro flask equipped with a motor stirrer, and 11 ml of propylene glycol was added.
was added to dissolve both substances, and the mixture was immersed in an oil bath previously adjusted to a constant temperature of 150°C.

Stirring was performed at 150° C. while passing nitrogen gas through the mixture to remove propylene glycol.

Temporarily stop stirring and add 4.57 (0.015 mol) of methyl stearate to the resulting melt of sucrose and alkali carbonate.
was added, and the mixture was reacted at 150° C. for 4 hours while stirring again.
The reaction mixture was purified in the same manner as in Example 1, and 3.5y
A sucrose fatty acid ester was obtained. Example 3 5.27 (0.015 mol) of sucrose and 0.87 (0.006 mol) of anhydrous potassium carbonate were reacted as described in Example 1 to obtain a melt of sucrose and alkali carbonate, To this were added 0.17 t (0.0003 mol) of potassium stearate and 4.5 t (0.015 mol) of methyl stearate.

The reaction was carried out at 155° C. for 2 hours while stirring and bubbling nitrogen gas to distill off the produced methanol. The reaction mixture was purified in the same manner as in Example 1. In this reaction, potassium stearate was used, but it was changed to stearic acid during acid treatment, and the mixture with unreacted methyl stearate could be recovered with ethyl acetate. 6.5y of sucrose stearate as a white fine powder was obtained. Monoester content 39. ．． 0%, diester 44.0%, and triester 17.0%. Example 4 Sucrose 5.27 (
0.015 mol) and anhydrous potassium carbonate 1.07 (0.0
075 mol) was reacted in the same manner as described in Example 1 to obtain a melt of sucrose and alkali carbonate.

To this, potassium stearate 0.17 (0.0003 mol) and methyl stearate 9.07 (0.030 mol)
was added and reacted at 150° C. for 3 hours with stirring. The reaction mixture of dark brown solid was purified in the same manner as in Example 1 to obtain 8.07 g of sucrose stearate as a white fine powder. Example 5 A melt of sucrose and alkali carbonate was prepared in the same manner as in Example 4, and 0.17 (0.0
．． 0003 mol) and 5.2 t (0.015 mol) of propylene glycol monostearate were added.

The reaction was carried out at 150° C. for 2 hours while stirring and bubbling nitrogen gas to remove generated propylene glycol.
The reaction mixture appeared as a homogeneous brown paste. It was purified in the same manner as in Example 1 to obtain sucrose stearate 4,77 as a white fine powder. Example 6 5.2 f7 (0.015 mol) of sucrose and 0.8 y (0.006 mol) of anhydrous potassium carbonate are reacted as described in Example 1, and after removal of water, 0.8 y (0.006 mol) of potassium stearate is reacted.
3y (0,0009 mol) and propylene glycol distearate 4.6y (0.0075 mol) were added.

The reaction was carried out at 155° C. for 3 hours while nitrogen gas was passed through and the produced propylene glycol was removed with stirring. The reaction mixture was a homogeneous dark brown paste, and it was purified in the same manner as described in Example 1 to obtain 7.3 t of sucrose stearate as a white fine powder. The monoester content was 32.0%, diester 53.1%, and triester 14.9%. Example 7 5.2 y (0.015 mol) of sucrose and 0.87 y (0.006 mol) of anhydrous potassium carbonate were reacted as described in Example 1, and after removing water, 0.3 y of potassium stearate was added.
(0.0009 mol) and monostearin 5.4 t (0.0009 mol).
015 mol) was added.

Glycerin produced was distilled off while stirring at 155°C.

Glycerin was distilled off after 1 hour and 30 minutes.

At this point, the reaction was terminated. The homogeneous brown reaction mixture was purified in the same manner as in Example 1 to obtain 5.3 t of sucrose stearate as a white fine powder. Example 8 A sucrose ester was synthesized in the same manner as in Example 7 using triglyceride as a fatty acid ester.

5.2y' (0.015 mol) of sucrose and 0.8y (0.006 mol) of anhydrous potassium carbonate are reacted as described in Example 1, and water is removed to form a melt of sucrose and alkali carbonate. and potassium stearate 0.37 (
0.0009 mol) and hydrogenated beef tallow oil (tristearin 7
0%, tripalmitin 30%, oxidation 0.08) 4.39
added. Glycerin produced was removed while stirring at 165°C, and the mixture was reacted for 2 hours.

The homogeneous dark brown reaction mixture was purified in the same manner as in Example 1,
A white fine powder of 5.27 sucrose stearate was obtained. Example 9 Sucrose laurate was synthesized in almost the same manner as in the previous example.

5.2 y (0.015 mol) of sucrose and 0.8 y (0.006 mol) of anhydrous potassium carbonate are reacted as described in Example 1, and the water is removed to form a melt of sucrose and alkali carbonate. generated. Add to this 0.1t of potassium stearate (
0.0003 mol) and 3.2 t (0.0003 mol) of methyl laurate.
015 mol) was added. The reaction was carried out at 150° C. for 2 hours while stirring to remove generated methanol. The reaction mixture was purified in the same manner as in Example 1 to obtain 3.9y of sucrose laurate as a white fine powder. Comparative Example 1 Sucrose 5.2f (0,015 mol), anhydrous potassium carbonate 1.07 (0.0075 mol) and methyl stearate 4
．． 57 (0.015 mol) in a 10
It was placed in a 0CC Mitsuro flask and immersed in an oil bath that had been adjusted to a constant temperature of 150°C.

Nitrogen gas was passed through one end of the Mitsuro flask, and a condenser was attached to the other end. Although the reaction was carried out at 150° C. for 4 hours with stirring, the reaction was heterogeneous and no sucrose fatty acid ester was obtained. Comparative Example 2 1.0y' (0.0075 mol) of anhydrous potassium carbonate and 4.5y (0.015 mol) of methyl stearate were placed in a 100CC Mitsuro flask equipped with a motor stirrer, and
It was immersed in an oil bath kept at a constant temperature of 0°C.

Claims (1)

[Claims] 1. A method for producing a sucrose ester, which comprises heating a melt of sucrose and a carbonate of potassium or/and sodium and a long-chain fatty acid ester to carry out a transesterification reaction.