JP2010280604A - Method for producing glycerin monofatty acid ester - Google Patents

Abstract

Provided is a method for producing a glycerin monofatty acid ester with a high selectivity at a high conversion rate by a simple process without using a solvent.
SOLUTION: General formula (1)
R ¹ —COOH (1)
(R ¹ is an alkyl group having 8 to 25 carbon atoms)
In which the fatty acid and glycerin are reacted in the presence of an acid catalyst to produce a glycerin monofatty acid ester, the tip peripheral speed of the stirring blade being 2 m / s or more, And it is the manufacturing method of the glycerol mono-fatty acid ester made to react in the temperature range of 60-150 degreeC, mixing on stirring conditions 1000 times / h or more of passes.
[Selection figure] None

Description

  The present invention relates to a method for producing a glycerin monofatty acid ester with a high selectivity at a high conversion rate by a simple process without using a solvent.

Glycerin monofatty acid esters (hereinafter also referred to as “monoglycerides”) are useful and widely used as food additives, emulsifiers and moisturizers for cosmetics, industrial emulsifiers, antistatic agents, oily agents for lubricating oils, and the like.
This monoglyceride is usually produced by direct esterification reaction from glycerin and fatty acid, or by transesterification of glycerin and fat. In these reactions, generally, a mixture of glycerin, monoglyceride, diglyceride and triglyceride is formed, and the content of monoglyceride calculated excluding glycerin is about 40 to 50% by mass in the ester mixture.
For this reason, as a method for obtaining a high-purity glycerin monofatty acid ester, a mixture of glycerin monofatty acid ester, glycerin difatty acid ester, and glycerin trifatty acid ester is obtained by directly reacting fat and glycerin in the presence of an alkali catalyst. A method of obtaining only glycerin monofatty acid ester by distillation is employed. However, since this method collects and re-reacts products other than the glycerin monofatty acid ester, the equipment becomes large.

On the other hand, a method for directly obtaining a high-purity glycerin monofatty acid ester by using an organic solvent is known.
For example, Patent Document 1 discloses a method for producing a monoglyceride in which an alkali catalyst, a fatty acid or a fatty acid alkyl ester are mixed and reacted with glycerin, and then the reaction mixture is transesterified in the presence of an organic solvent and an alkali catalyst. It is disclosed. However, this method requires a two-step process and has a problem with productivity.
Patent Document 2 discloses a method for producing a glycerin monofatty acid ester using methyl lactate as a solvent without using a catalyst, and Patent Document 3 discloses a glycerin monofatty acid ester using t-butanol as an acid catalyst and a solvent. The manufacturing method is disclosed. However, since the methods of Patent Documents 2 and 3 use a protic solvent, they may react with glycerin and fatty acids to reduce selectivity.

Furthermore, Patent Document 4 discloses a method for producing a monoglyceride including a mixing operation in which the tip peripheral speed of the stirring blade is 3 m / s or more and the number of passes is 0.1 times / hr or more with respect to glycerin and fatty acid. . In this method, a product having a monoglyceride content of 55% by mass or more can be obtained in a short time directly from glycerin and a fatty acid without using a catalyst or a solvent. In general, the number of passes when using such a technique is about 100 times / hr.
In Patent Document 5, a fatty acid, a ketone or an aldehyde, and glycerins are reacted in the presence of a catalyst to obtain an α-monoglyceride ketal, and then the ketal is deketalized to produce an α-monoglyceride. A method is disclosed. In this method, a high-quality α-monoglyceride having a purity of 90% or more can be produced.

Japanese Patent Laid-Open No. 1-268663 US Patent Application Publication No. 2002-0120159 European Patent Application No. 1672053 JP 2003-252829 A JP 2001-181271 A

  An object of the present invention is to provide a method for producing a glycerin monofatty acid ester with a high selectivity under a high fatty acid conversion rate by a simple process without using a solvent.

The present inventors have found that the above-mentioned problem can be solved by reacting fatty acid and glycerin in the presence of an acid catalyst under specific stirring conditions and a temperature range.
That is, the present invention relates to the general formula (1)
R ¹ —COOH (1)
(In the formula, R ¹ represents an alkyl group having 8 to 25 carbon atoms.)
In which the fatty acid and glycerin are reacted in the presence of an acid catalyst to produce a glycerin monofatty acid ester, the tip peripheral speed of the stirring blade being 2 m / s or more, And the manufacturing method of the glycerol mono-fatty acid ester made to react in the temperature range of 60-150 degreeC, mixing under stirring conditions 1000 times / h or more of passes.

  According to the present invention, a glycerol monofatty acid ester is efficiently produced with a selectivity of 60% or more by a simple process without using a solvent at a high selectivity under a high conversion rate, for example, at a fatty acid conversion rate of 90% or more. be able to.

  The method for producing a glycerin monofatty acid ester of the present invention comprises a fatty acid represented by the following general formula (1) and glycerin in the presence of an acid catalyst with a tip peripheral speed of 2 m / s or more and a pass The reaction is performed in a temperature range of 60 to 150 ° C. while mixing under stirring conditions of 1000 times / h or more.

[fatty acid]
The fatty acid used as a raw material in the present invention has a structure represented by the following general formula (1).
R ¹ —COOH (1)
In General formula (1), R < ¹ > shows a C8-C25 alkyl group. This alkyl group may be linear or branched, and is preferably an alkyl group having 11 to 21 carbon atoms, more preferably 13 to 17 carbon atoms.
Specific examples of R ¹ include various alkyl groups such as various nonyl groups, various undecyl groups, various tridecyl groups, various pentadecyl groups, various heptadecyl groups, and various nonadecyl groups. In addition, various alkyl groups mean the various isomers in the alkyl group of the same carbon number.

Specific examples of the fatty acid represented by the general formula (1) include various decanoic acids, various dodecanoic acids, various tetradecanoic acids, various hexadecanoic acids, various octadecanoic acids, and various alkanoic acids such as various icosanoic acids. Various alkanoic acids refer to various isomers in alkanoic acids having the same carbon number.
Among these fatty acids, linear fatty acids are preferable from the viewpoint of use and availability of the glycerin monofatty acid ester obtained, and capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, etc. Are more preferable, and myristic acid, palmitic acid, and stearic acid are more preferable.
Said fatty acid can be used individually by 1 type or in combination of 2 or more types.

[Acid catalyst]
In the method of the present invention, an acid catalyst is used as a catalyst. From the viewpoint of reactivity, the acid catalyst preferably has an acid dissociation index (pKa) at 25 ° C. of 3 or less, and more preferably 2 or less.
Specific examples thereof include sulfuric acid (second stage pKa in aqueous solution: 1.9), phosphoric acid (pKa: 2.2), p-toluenesulfonic acid (pKa: -2.6), benzenesulfonic acid (pKa:- 6.5), organic sulfonic acids such as trifluoromethanesulfonic acid (pKa: -13) and Nafion [registered trademark of DuPont, perfluorosulfonic acid / PTFE copolymer] dispersion (pKa: about -6), phosphotungsten Examples include heteropolyacids such as acid (pKa: 1.6) and phosphomolybdic acid (pKa: 2.4). Among these, sulfuric acid and organic sulfonic acid are preferable, and sulfuric acid and paratoluenesulfonic acid are particularly preferable.
Said acid catalyst can be used individually by 1 type or in combination of 2 or more types.
As the acid dissociation index (pKa), for example, the acid dissociation index described in the Chemical Handbook edited by the Chemical Society of Japan (Revised 3rd edition, published June 25, 1984, Maruzen Co., Ltd.) can be used.
The amount of the acid catalyst used is preferably from 1 to 20 mol%, more preferably from 2 to 17 mol%, still more preferably from 5 to 15 mol%, from the viewpoint of reaction rate and side reaction suppression.

The glycerin used as the raw material is not particularly limited, but preferably has a purity of 95% or more.
The amount of glycerin charged is preferably 3 mol times or more, more preferably 4 to 25 mol times, still more preferably 5 to 20 mol times with respect to the fatty acid, from the viewpoint of reaction rate and monoglyceride selectivity.

[Stirring conditions]
In the present invention, the above-mentioned fatty acid and glycerin are mixed with each other while stirring the tip peripheral speed of the stirring blade at 2 m / s or more and under the stirring conditions of 1000 times / h or more as defined by the following formula. The reaction is performed by heating in the presence of a catalyst. By reacting the fatty acid and glycerin in an emulsified state under such stirring conditions, a glycerin monofatty acid ester is produced with high selectivity.
The tip peripheral speed of the stirring blade is 2 m / s or more, preferably 2 to 10 m / s, more preferably 3 to 6 m / s, from the viewpoint of the selectivity of the glycerin monofatty acid ester.
As the stirrer used in the present invention, an internal insertion type stirrer is preferable. In this case, the number of passes is 1000 times / hr or more, preferably 1000 to 3000 times / hr, from the viewpoint of the selectivity of glycerin monofatty acid ester. 1000-2000 times / hr is more preferable.
The number of passes is a value defined by the following equation.
Number of passes (times / h) = Nq · n · d ³ · 1000 · 60
Nq: discharge coefficient (0.2 for high-speed rotary shearing type stirrer),
n: rotational speed (r / min), d: blade diameter (m)
[(Reference) “Theory and Practice of Emulsification and Dispersion (Practical)”, Special Machine Industries Co., Ltd.

In the present invention, as the stirrer, a high-speed rotating centrifugal radiation stirrer and a high-speed rotating shear stirrer are preferable, and a high-speed rotating shear stirrer is more preferable.
A high-speed rotating centrifugal radiation type stirrer (disper mixer) is a stirrer that operates a toothed disk-shaped impeller in which circular saw blades are alternately bent up and down at a peripheral speed of about 10 to 30 m / s. Specifically, T.M. K. A homodisper etc. are mentioned.
A high-speed rotary shear type agitator (homomixer) is a combination of a rotating blade (turbine blade) and a stationary ring (stator) that rotate at high speed (around 10 to 30 m / s) and is provided between the two. It is a stirrer that atomizes and homogenizes a fluid by using a strong shearing action and impact force that occurs in a fine gap, and there are an internal insertion type and a continuous processing type.
The internal insertion type is one in which a processing solution is placed in a container from above and stirred batchwise. As an example of a commercial product, T.I. K. Homomixer (trade name), Ultra Turrax (trade name) manufactured by IKA Japan Corporation, and Biomixer (trade name) manufactured by Nippon Seiki Seisakusho Co., Ltd. may be mentioned.
The continuous processing method type is one in which a processing liquid is passed through a cylindrical vessel with a fluid inlet and outlet and a turbine and a stator inserted in it, and continuously stirred. T.M. K. Pipeline homomixer, T.W. K. Homomic line mill, T.W. K. Examples include homomic line flow and milder manufactured by Ebara Corporation.
In the present invention, an internal insertion type high-speed rotary shearing type stirrer is particularly preferable.

In the present invention, the fatty acid and glycerin are reacted in the temperature range of 60 to 150 ° C. while mixing under the stirring conditions in the presence of an acid catalyst. If reaction temperature exists in the said range, glycerol mono fatty-acid ester can be obtained with high selectivity. From the viewpoint of selectivity of glycerin monofatty acid ester, the reaction temperature is preferably 80 to 145 ° C, more preferably 100 to 140 ° C.
In addition, the reaction is usually performed while introducing nitrogen into the reaction system at a reduced pressure of about 0.01 to 0.09 MPa or at normal pressure to remove the generated water from the system in order to improve the reaction rate. Is preferred.
The reaction time is desirably such that the fatty acid conversion is 90% or more, preferably 95% or more. The reaction time depends on the reaction temperature, stirring conditions, the amount of acid catalyst used and the like, but is usually about 1 to 10 hours, preferably 3 to 5 hours.

According to the production method of the present invention, the fatty acid conversion rate reaches 90% or more, preferably 95% or more, and the selectivity for glycerin monofatty acid ester is usually 60 mol% or more. Further, by-products are usually produced at a ratio of less than 40 mol%, which is mainly glycerin difatty acid ester.
In the present invention, excess glycerin is distilled off from the reaction product obtained as described above under reduced pressure, and then the acid catalyst is removed by washing with water to obtain a glycerin monofatty acid ester having a purity of about 65% or more. Obtainable.
The glycerin monofatty acid ester having a purity of about 65% or more is useful as an emulsifier or moisturizer for food additives, cosmetics and the like, an industrial emulsifier, an antistatic agent, and an oily agent for lubricating oil.

  The reason for the improvement in selectivity in the present invention is not yet elucidated, but the glycerol monofatty acid ester formation reaction proceeds at the interface between the fatty acid and glycerol, and the overreaction and transesterification that cause the decrease in selectivity are mainly performed. Therefore, it is considered that, as a result of emulsification by the stirring force of the present invention, the glycerin monofatty acid ester formation reaction is advantageously promoted and the selectivity is improved by increasing the area of the interface. In addition, the higher the reaction temperature, the faster the reaction rate, but the reaction rate of the esterification reaction to the diester or higher proceeding in the fatty acid layer is also increased, so the selectivity is considered to be lowered. The reaction conditions of the present invention are that the monoesterification reaction is accelerated by increasing the interfacial area of fatty acid and glycerin, and the reaction rate of the esterification reaction to more than the diester proceeding in the fatty acid layer by optimizing the reaction temperature It is considered that the selectivity could be improved by suppressing.

Example 1
In a 2 L glass container equipped with a homomixer (manufactured by Primics Co., Ltd., trade name: TK homomixer), 552 g (6.0 mol) glycerin (Kao Corporation pharmacopoeia glycerin), palmitic acid (Kao stock) Company-made Lunac P-95 (78 g, 0.30 mol) and p-toluenesulfonic acid monohydrate (manufactured by Wako Pure Chemical Industries, Ltd.) 5.8 g (0.030 mol) were charged as a catalyst at 105 ° C. While flowing nitrogen through the system (nitrogen flow rate: 250 mL / min), the rotation speed: 6000 r / min, the tip peripheral speed of the stirring blade: 3.1 m / s, and the number of passes: 1097 times / h, The reaction was performed for 5 hours.
After completion of the reaction, the solution was trimethylsilylated, followed by gas chromatography [column: Ultra-alloy capillary column 15.0 m × 250 μm (manufactured by Frontier Laboratories), detector: FID, injection temperature: 300 ° C., detector temperature: 350 ° C., He flow rate: 4.6 mL / min. The product was quantified.
As a result, the fatty acid conversion was 96% and the monoglyceride selectivity was 65 mol%.
Production conditions and results are shown in Table 1.
The fatty acid conversion rate and monoglyceride selectivity were calculated according to the following formulas.
Fatty acid conversion (%) = [Mole amount of residual fatty acid / [Mole amount of raw material fatty acid] × 100
Monoglyceride selectivity (mol%) = [Mole amount of produced monoglyceride / (Mole amount of produced monoglyceride + Mole amount of produced diglyceride + Mole amount of produced triglyceride)] × 100

Examples 2 to 4 and Comparative Examples 1 and 2
The reaction was performed in the same manner as in Example 1 under the production conditions shown in Table 1. The results are shown in Table 1.
The mechanical stirrer used in Comparative Example 1 was manufactured by T.M. K. It is a homomixer.

From Table 1, according to the production methods of Examples 1 to 3, when paratoluenesulfonic acid was used as a catalyst, the fatty acid conversion reached 95 to 96% in 3 to 5 hours, and 65 to 73 mol%. It turns out that glycerol mono-fatty acid ester (monoglyceride) is obtained with high selectivity. In Example 4 using sulfuric acid as a catalyst, the fatty acid conversion reached 95% in 15 hours, and a glycerin monofatty acid ester was obtained with a high selectivity of 78 mol%.
On the other hand, in Comparative Example 1 in which the number of passes was small, the fatty acid conversion rate reached 98% in 3 hours, but the selectivity of glycerin monofatty acid ester was as low as 58 mol%. Further, in Comparative Example 2 where the reaction temperature is high, the fatty acid conversion rate reaches 99% in 0.5 hours, but the selectivity of glycerin monofatty acid ester is extremely low at 45 mol%.
From the above, the method of the present invention in which a fatty acid and glycerin are reacted in the presence of an acid catalyst under a specific stirring condition and temperature range is extremely advantageous as a method for producing a glycerin monofatty acid ester.

Claims (5)

General formula (1)
R ¹ —COOH (1)
(In the formula, R ¹ represents an alkyl group having 8 to 25 carbon atoms.)
In which the fatty acid and glycerin are reacted in the presence of an acid catalyst to produce a glycerin monofatty acid ester, the tip peripheral speed of the stirring blade being 2 m / s or more, And the manufacturing method of the glycerol mono-fatty acid ester made to react in the temperature range of 60-150 degreeC, mixing under stirring conditions 1000 times / h or more of passes.   The manufacturing method of the glycerol mono-fatty acid ester of Claim 1 which is 3 or more by the molar ratio of glycerol with respect to a fatty acid.   The manufacturing method of the glycerol mono fatty acid ester of Claim 1 or 2 whose acid dissociation constant (pKa) in 25 degreeC is a 3 or less thing.   The manufacturing method of the glycerol mono-fatty acid ester of Claim 3 whose acid catalyst is at least 1 sort (s) chosen from organic sulfonic acid and a sulfuric acid.   The manufacturing method of the glycerol mono-fatty acid ester in any one of Claims 1-4 whose usage-amount of an acid catalyst is 1-20 mol% with respect to a fatty acid.