JP2008297290A - Method for producing alkylgalactoside - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an alkylgalactoside in a high yield while suppressing the production of highly condensed products, and the alkylgalactoside obtained by the method. <P>SOLUTION: In the method for producing the alkylgalactoside, galactose is glycosidated using a 7-22C branched aliphatic alcohol, provided that the amount of the branched aliphatic alcohol used is 8-25 times the amount of galactose by mol. The alkylgalactoside obtained by the production method is also provided. The glycosidation is preferably carried out in the presence of an acid catalyst, in particular, an aromatic sulfonic acid. The reaction temperature for the glycosidation is preferably 50-150°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an alkyl galactoside having a low content of highly condensed products and unreacted galactose, and an alkyl galactoside obtained by the method.

Alkyl glycosides, which are sugar derivatives, are hypoallergenic surfactants and are known to act as foam stabilizers for other anionic surfactants.
One common method for producing alkyl glycosides is to directly react a sugar and a higher alcohol in the presence of an acid catalyst, and many proposals have been made (see, for example, Patent Document 1).

However, many difficulties are associated with the production of alkyl glycosides by conventional methods. Among them, one of the important problems is that a high condensate is generated by condensation between sugars or sugar and generated alkylglycoside, and generated alkylglycosides, and the yield decreases.
For example, when the production of alkyl galactoside is attempted using galactose as a raw material sugar by the method for producing alkyl glycoside disclosed in Patent Document 2 and Patent Document 3, production of a high condensate is remarkable and the yield is remarkably reduced. Resulting in. Further, when a branched aliphatic alcohol is used as the higher alcohol, not only the production of a high condensate but also a decrease in the reaction rate of galactose is observed, and thus a lot of unreacted galactose remains.
In addition, since the reaction end product-containing solution becomes a solid-liquid two-phase system due to the formation of a high condensate or the remaining unreacted galactose, it is often used in purification processes such as removal of excessive higher alcohol. Accompanied by difficulties.

  As described above, many proposals relating to a method for producing an alkyl glycoside have been made, but most of these proposals use glucose as a raw sugar, and little is disclosed regarding alkyl glycosidation of galactose. Therefore, a technical problem associated with a method for producing an alkyl galactoside using galactose as a starting material is not known.

JP 2001-151789 A JP-A-4-224598 Japanese Patent Laid-Open No. 62-292789

  In producing alkyl galactoside by reacting galactose with a branched aliphatic alcohol having 7 to 22 carbon atoms, the production of alkyl galactoside is suppressed in a high yield by suppressing the formation of a high condensate and residual unreacted galactose. It is an object of the present invention to provide an alkyl galactoside having a low content of highly condensed products and unreacted galactose.

The present inventors have used alkyl galactoside with an improved yield by suppressing the formation of a high condensate and residual unreacted galactose by using an excess of 8 times mole or more of the branched aliphatic alcohol relative to galactose. It was found that can be obtained.
That is, the present invention provides the following (1) to (2).
(1) A method for producing an alkyl galactoside in which galactose is glycosidated using a branched aliphatic alcohol having 7 to 22 carbon atoms, and the branched aliphatic alcohol is used at a ratio of 8 to 25-fold mol with respect to galactose. , Alkylgalactoside production method (2) Alkylgalactoside obtained by the production method of (1) above.

  According to the method of the present invention, it is possible to produce an alkyl galactoside with a low content of a high sugar condensate or unreacted galactose in a high yield. Moreover, the alkyl galactoside with little content of a highly condensed product and unreacted galactose can be provided.

In the method for producing an alkyl galactoside of the present invention, the alkyl galactoside is produced by glycosidation using galactose and a branched aliphatic alcohol having 7 to 22 carbon atoms.
There is no restriction | limiting in particular as C7-22 branched aliphatic alcohol used as a raw material in this invention, For example, various branched-chain heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol Hexadecanol, heptadecanol, octadecanol, nonadecanol, eicosanol, heneicosanol, docosanol, unsaturated alcohol, an alkylene oxide adduct thereof, and a mixture thereof.

  Examples of the branched chain heptanol include 1,4-dimethylpentanol, 3-methylhexanol, 4-methylhexanol, and 5-methylhexanol. Examples of the branched chain octanol include 1,1,2-trimethylpentanol, 1, Examples include 1,4-trimethylpentanol, 2,2-dimethylhexanol, 2-methylheptanol, 5-methylheptanol, 2-ethylhexanol, and the like, and branched chain nonanol includes 1-methyloctanol, 6-methyl Examples include octanol and 8-methyloctanol.

  Examples of the branched chain decanol include 3,7-dimethyloctanol, 2-methylnonanol, and 8-methylnonanol. Examples of the branched chain undecanol include 1-methyldecanol, 2-methyldecanol, 9 -Methyldecanol and the like are mentioned, and the branched chain dodecanol includes 2-butyloctanol, 2-methylundecanol, 10-methylundecanol and the like, and the branched chain tridecanol is 2-methyldodecanol, 11-methyl dodecanol etc. are mentioned, As a branched chain tetradecanol, 2-methyl tridecanol, 12-methyl tridecanol, etc. are mentioned.

Examples of the branched-chain pentadecanol include 2-methyltetradecanol and 13-methyltetradecanol. Examples of the branched-chain hexadecanol include 2-hexyldecanol, 2-methylpentadecanol, and 14-methylpentadecanol. Examples of the branched chain heptadecanol include 2-methylhexadecanol and 15-methylhexadecanol. Examples of the branched chain octadecanol include 2-methylheptadecanol and 16-methylheptaanol. Examples of the branched chain nonadecanol include 2-methyloctadecanol and 17-methyloctadecanol.
Examples of the branched chain eicosanol include 2-octyldodecanol, 2-methylnonadecanol, and 18-methylnonadecanol. Examples of the branched chain eicosanol include 2-methyleicosanol and 19-methyleicosanol. Examples of the branched chain docosanol include 2-methylheneicosanol and 20-methylheneicosanol.

Examples of branched unsaturated alcohols include unsaturated monoterpene alcohols such as geraniol, nerol, citronellol and linalool, unsaturated sesquiterpene terpene alcohols such as farnesol and nedridol, unsaturated diterpene alcohols such as phytol and geranylgeraniol, and the like. .
Among these, branched aliphatic alcohols having 7 to 22 carbon atoms, particularly 8 to 15 carbon atoms are preferable from the viewpoint of application development, safety, and the like.
These branched aliphatic alcohols can be used alone or in admixture of two or more at any ratio.

  Commercially available branched aliphatic alcohols having 7 to 22 carbon atoms include Condea's ISOFOL series, Kyowa Hakko Chemical Co., Ltd. Octanol, Nonanol, Decanol, Tridecanol, Oxocol 900, Nissan Chemical Co., Ltd. isostearyl alcohol, Ziegler NAFOL 1214 from Shell Chemicals Japan, Lineball 11, Lineball 922, Neodol 23 from Mitsubishi Chemical Corporation, Dovanol 23 from Mitsubishi Chemical Corporation, Diamond Doll 11, Diamond Doll 915, Diamond Doll 115L, EXXAL7 from ExxonMobil, EXXAL10, EXXAL13, Sasol Lial123, SAFOL23, and the like.

  In this invention, the usage-amount of the said branched aliphatic alcohol is the range of 8-25 times mole with respect to galactose. If the amount of the branched aliphatic alcohol used is 8 times mol or more, the formation of a highly condensed product can be sufficiently suppressed, and if it is 25 times mol or less, there are technical and economic advantages. The preferable usage-amount of branched aliphatic alcohol is 9-22 times mole with respect to galactose, More preferably, it is 10-20 times mole.

The acid catalyst used in the glycosidation step is not particularly limited as long as it is usually used in a dehydration reaction, and a known one is used. For example, at least one selected from strongly acidic ion exchange resins based on paratoluenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, styrene-divinylbenzene copolymer, and the like. . Among these, aromatic sulfonic acids such as strongly acidic ion exchange resins based on benzenesulfonic acid, p-toluenesulfonic acid, styrene-divinylbenzene copolymer and the like are preferable, from the viewpoint of solubility in the higher alcohol. Paratoluenesulfonic acid is particularly preferred.
The amount of acid catalyst used is preferably 0.001 to 0.10 mole per mole of galactose. If the usage-amount of an acid catalyst exists in this range, both the reaction rate and the hue of the alkyl galactoside obtained will become favorable. The amount of the acid catalyst is more preferably 1 to 80 mmol, still more preferably 2 to 50 mmol, particularly preferably 3 to 20 mmol, per mol of galactose.

In the present invention, the reaction temperature between galactose and the branched aliphatic alcohol is usually 50 to 150 ° C, preferably 80 to 120 ° C, more preferably 100 to 120 ° C. From the viewpoint of the reaction rate, the reaction temperature is preferably 50 ° C. or higher, and is preferably 150 ° C. or lower in order to suppress hue deterioration of the resulting alkylgalactoside.
The degree of reduced pressure in the reaction between galactose and the branched aliphatic alcohol is preferably 0.67 to 13.3 kPa, more preferably 2.7 to 8.0 kPa. From the viewpoint of dewatering efficiency, the degree of vacuum is preferably 13.3 kPa or less.

Here, an inert gas such as nitrogen may be blown in order to efficiently remove the by-product water. Since the amount of the inert gas blown differs depending on the amount of the raw material charged, it cannot be generally stated. For example, it is preferable to blow an inert gas of about 10 to 50 ml / min with respect to the charge amount of 0.10 mol of galactose. .
Since the reaction time depends on the reaction conditions, it cannot be determined unconditionally. However, it is preferable to appropriately monitor the consumption of raw materials and the amount of product produced, and to terminate the reaction at the end of the reaction.

  In the present invention, alcohol as a raw material for alkylgalactoside can be used as a reaction solvent, but an auxiliary solvent may be used to adjust the concentration of the reaction system. However, it is preferable that the auxiliary solvent to be used has a boiling point high enough not to boil even under the reaction conditions for producing alkylgalactoside and does not affect the reaction at all.

After completion of the reaction, it is preferable to neutralize the catalyst by adding a basic substance in order to suppress the progress of sugar condensation at the stage where the reactor is returned to normal pressure. The basic substance used for neutralization is not particularly limited, and examples thereof include NaOH, KOH, Na ₂ CO ₃ , NaHCO ₃ , NH ₃ , and strongly basic ion exchange resins. Among these, NaOH and KOH are preferably used from the viewpoints of economy, solubility, and handleability.

The method for calculating the average degree of sugar condensation of the reaction end product is not particularly limited. In the present invention, after the reaction end product is acetylated, it is analyzed by gel permeation chromatography (hereinafter referred to as “GPC”), and the average sugar condensation degree can be calculated from the area ratio of each component.
The analysis by GPC uses, for example, a product name manufactured by Tosoh Corporation, LC-8020 high-pressure gradient system, and as a column, product names manufactured by Tosoh Corporation, TSK-GEL G2000HXL7.8 * 300 and TSK-GEL G1000HXL7. This can be done by using 8 * 300 in series and using tetrahydrofuran as the developing solvent. Further, as a detector, a trade name, RI8020, manufactured by Tosoh Corporation can be used.
In addition, the general meaning of “high condensate” is not particularly limited, but in the present invention, as a result of GPC analysis of the reaction end product, it means an alkyl galactoside or oligosaccharide having a sugar condensation degree of 4 or more. To do.

  The alkyl galactoside of the present invention can be obtained by the above-described method for producing an alkyl galactoside of the present invention. The alkyl galactoside of the present invention is a composition in which one kind of compound or two or more kinds of alkyl galactosides are mixed, and is characterized by a low content of highly condensed products and unreacted galactose. The content of the high condensate and unreacted galactose is not particularly limited, but usually the content of the high condensate is 3 mol% or less and the content of unreacted galactose is about 20 mol% or less.

  The alkyl galactoside of the present invention is useful as a hypoallergenic surfactant and can also be used as a foam stabilizer for other anionic surfactants. In recent years, it has been reported that alkylgalactoside has a coaggregation-inhibiting effect on oral bacteria (see, for example, JP-A-2006-124384 and JP-A-2006-182692), and is incorporated into a composition for oral cavity. It is also effective.

Example 1
Weighing 0.52 g (2.7 mmol) of paratoluenesulfonic acid monohydrate, 100 g (0.56 mol) of galactose, and 1084 g of 2-ethylhexanol (8.3 mol, 15 times mol of galactose) into a 2 L 4-neck flask. Then, a nitrogen blowing port and a Liebig condenser were attached, and the temperature was raised to 115 ° C. After the temperature increase, the pressure inside the system was set to 12 kPa (90 mmHg), and the dehydration reaction was started. At this time, nitrogen was blown into the reaction mixture solution at 100 ml / min, and the reaction was carried out for 3.25 hours so as to efficiently remove the generated water.
After the reaction is completed, the pressure is returned to normal pressure, and in the state where the reaction product solution is about 80 ° C., 0.23 g (2.7 mmol) of a 48 mass% sodium hydroxide aqueous solution is added to neutralize the 2-ethylhexyl galactoside. Obtained. The obtained 2-ethylhexyl galactoside was subjected to GPC analysis (column: manufactured by Tosoh Corporation, trade name, TSK-GEL G2000HXL7.8 * 300 and TSK-GEL G1000HXL7.8 * 300 used in series, developing solvent: tetrahydrofuran), The molar ratio of unreacted galactose was 0%, and the obtained 2-ethylhexyl galactoside had an average sugar condensation degree of 1.17, and a high condensation product having a sugar condensation degree of 4 or more had a molar ratio of 0.01% or less. It was.

Comparative Example 1
The procedure of Example 1 was repeated except that the 2 L 4-neck flask in Example 1 was changed to a 500-ml 5-neck flask and 362 g of 2-ethylhexanol (2.8 mol, 5 times mol of galactose) to give 2-ethylhexyl. Galactoside was obtained. As a result of GPC analysis of the obtained 2-ethylhexyl galactoside in the same manner as in Example 1, the molar ratio of unreacted galactose was 33.3%, and the average sugar condensation degree of the obtained 2-ethylhexyl galactoside was 1.40. The molar ratio of the high condensate having a sugar condensation degree of 4 or more was 4.0%.

Example 2
Instead of 2-ethylhexanol in Example 1, 1054 g (6.7 mol, 15 times mol of galactose) of a decanol isomer mixture (trade name decanol manufactured by Kyowa Hakko Chemical) was used, and 0.42 g (2 0.2 mmol), 80 g (0.44 mol) of galactose, 5.3 kPa (40 mmHg) in the system, 4 hours of reaction time, and 0.19 g (2.2 mmol) of 48% by mass sodium hydroxide aqueous solution. The operation of Example 1 was performed to obtain decylgalactoside. The obtained decylgalactoside was subjected to GPC analysis in the same manner as in Example 1. As a result, the molar ratio of unreacted galactose was 0%. The resulting decylgalactoside had an average degree of sugar condensation of 1.15 and a degree of sugar condensation of 4. The molar ratio of the above highly condensed product was 0.01% or less.

Comparative Example 2
The procedure of Example 2 was repeated except that the 2 L 4-necked flask in Example 2 was changed to a 500 ml 5-necked flask and the decanol isomer mixture was changed to 351 g (2.2 mol, 5 times mol of galactose) to obtain decylgalactoside. Obtained. The obtained decylgalactoside was subjected to GPC analysis in the same manner as in Example 1. As a result, the molar ratio of unreacted galactose was 26.3%, and the average degree of sugar condensation of the obtained decylgalactoside was 1.45, the degree of sugar condensation. However, the molar ratio of the high condensate of 4 or more was 6.1%.

Example 3
In place of 2-ethylhexanol in Example 1, 861 g (5.0 mol, 15 times mol of galactose) of undecanol isomer mixture (trade name: Diadol 11 manufactured by Mitsubishi Chemical) was used and 0.32 g of paratoluenesulfonic acid ( 1.7 mmol), 60 g (0.33 mol) of galactose, 5.3 kPa (40 mmHg) in the system, 6 hours of reaction time, and 0.14 g (1.7 mmol) of 48 mass% sodium hydroxide aqueous solution. Performed the operation of Example 1 to obtain undecylgalactoside.
The obtained undecylgalactoside was subjected to GPC analysis in the same manner as in Example 1. As a result, the molar ratio of unreacted galactose was 0%, and the average degree of sugar condensation of the obtained undecylgalactoside was 1.16, the degree of sugar condensation. However, the molar ratio of the high condensate of 4 or more was 0.01% or less.

Comparative Example 3
The procedure of Example 3 was repeated except that the 2 L 4-neck flask in Example 3 was changed to a 500-ml 5-neck flask and the undecanol isomer mixture was changed to 287 g (1.7 mol, 5 times mol of galactose). Got. The obtained undecyl galactoside was subjected to GPC analysis in the same manner as in Example 1. As a result, the molar ratio of unreacted galactose was 31.6%, and the average degree of sugar condensation of the obtained undecyl galactoside was 1.56. The molar ratio of the highly condensed product having a degree of condensation of 4 or more was 11.3%.

The sum of the molar ratio of unreacted galactose to galactose and the molar ratio of the high condensate to galactose obtained in Examples 1 to 3 and Comparative Examples 1 to 3, and the average degree of sugar condensation of the resulting alkyl galactoside It is a graph.

Claims (5)

  An alkyl galactoside, which is a method for producing an alkyl galactoside, wherein galactose is glycosidated using a branched aliphatic alcohol having 7 to 22 carbon atoms, wherein the branched aliphatic alcohol is used at a ratio of 8 to 25-fold mol with respect to galactose. Manufacturing method.   The method for producing an alkyl galactoside according to claim 1, wherein glycosidation is carried out in the presence of an acid catalyst.   The method for producing an alkyl galactoside according to claim 2, wherein the acid catalyst is an aromatic sulfonic acid.   The manufacturing method of the alkyl galactoside in any one of Claims 1-3 whose reaction temperature in glycosidation is 50-150 degreeC.   The alkyl galactoside obtained by the manufacturing method in any one of Claims 1-4.

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