JP2008195661A - Method for producing alkylglycoside - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a high-purity alkylglycoside in which the thermal decomposition of the alkylglycoside is inhibited by not heating to a high temperature, and impurities such as a non-reacted higher alcohol and a discolored substance can efficiently be separated and removed. <P>SOLUTION: The method for producing the alkylglycoside comprises the following steps (I) to (III): step (I): a step of preparing a crude alkylglycoside by reacting saccharides or a lower alkylglycoside with a higher alcohol or an alkylene oxide adduct thereof; step (II): a step of preparing a mixture by adding a hydrocarbon oil to the crude alkylglycoside; and step (III): a step of preparing the alkylglycoside by distilling the mixture under reduced pressure, wherein, the higher alcohol or the alkylene oxide adduct thereof is represented by the general formula (I): RO-(AO)<SB>n</SB>-H (I) (wherein, R is a 6-22C hydrocarbon group; A is a 2-4C alkanediyl group; and n is 0-5 in average). <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing an alkyl glycoside.

Alkyl glycoside, which is a sugar derivative, is a very good agent known as a hypoallergenic surfactant. Among them, alkyl galactoside is known to have a strong coaggregation inhibitory action against caries-causing bacteria. In recent years, the compound has attracted much attention (for example, Patent Document 1).
Alkyl glycosides are usually prepared by direct reaction of saccharide and higher alcohol directly in the presence of an acid catalyst, or by reacting saccharide and lower alcohol in the presence of an acid catalyst to prepare a lower alkyl glycoside, and then acetal exchange with higher alcohol. To produce an alkyl glycoside having the desired alkyl chain. In these methods, the higher alcohol is generally used in excess of the saccharide, and impurities such as alkyl glycosides produced by the reaction, unreacted higher alcohols and colored substances produced by the reaction (hereinafter referred to as impurities). It is necessary to separate the unreacted higher alcohol and impurities from the mixture.
As a method for separating unreacted higher alcohol, generally known distillation or the like is used. However, heating to a high temperature is essential for distillation. In general, the boiling point of higher alcohols is high, the viscosity of crude alkyl glycosides containing impurities such as unreacted higher alcohols and coloring substances is large, and the diffusion rate of unreacted higher alcohols in the interior is slow, so that it remains after distillation. This is because in order to reduce the amount of the unreacted higher alcohol, it is necessary to improve the fluidity of the crude alkyl glycoside at a high temperature. However, the thermal stability of alkyl glycosides is limited, and when heated to a high temperature, a part of the alkyl glycoside is decomposed, and at the same time, it is slightly present in the crude alkyl glycoside or is caused by the decomposition of the alkyl glycoside. Due to the modification of the reducing sugar, there are problems such as an unfavorable hue and odor of the alkylglycoside, and a high condensate.
In addition, in order to economically produce alkyl glycosides, it is important to recover the excess unreacted higher alcohol after separating it from the crude alkyl glycoside and reuse it. The quality of the unreacted higher alcohol to be recovered is lowered.

  As a means for solving the above-mentioned problem, a reaction product containing an excess of unreacted higher alcohol is made into a thin film using a thin-film distiller, and excess unreacted higher alcohol is evaporated at an extremely short residence time at a relatively high temperature. Has been proposed (for example, Patent Document 2). This method aims to suppress the thermal decomposition of the alkyl glycoside by shortening the residence time extremely, but the hue and the smell deterioration due to the thermal decomposition have not been sufficiently suppressed. In this method, it is very difficult to remove the unreacted higher alcohol from the crude alkyl glycoside.

  A method of separating alcohol at a relatively low temperature by adding a polar oil viscosity reducing agent to an alkyl glycoside has been proposed (for example, Patent Document 3). In this method, a viscosity reducing agent is added to lower the viscosity of the compound to suppress thermal decomposition and coloring of the alkyl glycoside. However, in the purification process, the viscosity reducing agent reacts with the alkyl glycoside to produce a by-product. In addition, there is a problem that it is difficult to remove the viscosity reducing agent, and the degree of freedom in blending is low.

  Or the separation method of the unreacted higher alcohol which does not require the heating to high temperature is proposed (for example, patent document 4). In this method, silicalite having a molecular sieving effect is used as an adsorbent, and a higher alcohol having a smaller molecular size than that of an alkylglycoside is preferentially adsorbed to purify the alkylglycoside. However, this method is not sufficient in terms of the degree of purification of the alkyl glycoside because the adsorption amount of the higher alcohol to the adsorbent is small and the selectivity of the adsorption of the alkyl glycoside and the higher alcohol is small.

  As a method for purifying long-chain alkyl glycosides, a method for extracting and separating long-chain alkyl glycosides using water has been proposed (for example, Patent Document 5). However, in this method, since the affinity between the unreacted higher alcohol and the alkyl glycoside is large, it is extremely difficult to completely extract only the alkyl glycoside.

WO 06/35821 pamphlet JP 58-194902 A Japanese Patent Laid-Open No. 62-192396 US Pat. No. 4,571,306 JP-A-1-249794

  The present invention provides a method for producing a high-purity alkylglycoside that suppresses thermal decomposition of alkylglycoside without heating to a high temperature, and can efficiently separate and remove impurities such as unreacted higher alcohols and colored substances. This is the issue.

The present inventors can easily separate and remove impurities such as unreacted higher alcohol and coloring substances remaining in the crude alkyl glycoside by reacting saccharides or derivatives thereof with higher alcohol by using hydrocarbon oil. And found out that the above problems can be solved.
That is, the present invention provides the following manufacturing method.
1. The following steps (I) to (III)
Step (I): a step of obtaining a crude alkyl glycoside by reacting a saccharide or a lower alkyl glycoside with a higher alcohol or an alkylene oxide adduct thereof,
Step (II): adding a hydrocarbon oil to the crude alkyl glycoside to obtain a mixture, and Step (III): step of distilling the mixture under reduced pressure to obtain an alkyl glycoside.
And higher alcohols or alkylene oxide adducts thereof are represented by the following general formula (I):

The manufacturing method of the alkyl glycoside represented by these.
(In the formula, R represents a hydrocarbon group having 6 to 22 carbon atoms, A represents an alkanediyl group having 2 to 4 carbon atoms, and n has an average value of 0 to 5).
2. After step (III), the following step (IV)
Process (IV): The manufacturing method of the alkyl glycoside of said 1 including the process of isolate | separating hydrocarbon oil.

  According to the method for producing an alkyl glycoside of the present invention, it is possible to suppress the thermal decomposition of the alkyl glycoside by not heating to a high temperature, and to efficiently separate and remove impurities such as unreacted higher alcohol and colored substances. Can be obtained.

[Step (I)]
Step (I) of the present invention is a step of obtaining a crude alkyl glycoside by reacting a lower alkyl glycoside, which is a saccharide or a derivative thereof, with a higher alcohol or an alkylene oxide adduct thereof. The crude alkyl glycoside is obtained by a well-known method. For example, a direct method in which a saccharide and a higher alcohol are directly reacted in the presence of an acid catalyst, or a reaction of a saccharide and a lower alcohol in the presence of an acid catalyst. A lower alkyl glycoside, which is a derivative of the resulting saccharide, is prepared, and then acetal exchanged with a higher alcohol to obtain an alkyl glycoside having the desired alkyl chain, which can be obtained according to the indirect method.

  In the present invention, monosaccharides, oligosaccharides or polysaccharides are used as saccharides used as a raw material. Specific examples of the polysaccharide include aldoses such as allose, altrose, glucose, idose, galactose, talose, ribose, arabinose, xylose, lyxose, and ketose fructose. Specific examples of oligosaccharides include maltose, lactose, sucrose, maltotriose and the like. Specific examples of the polysaccharide include hemicellulose, inulin, dextran, xylan, starch, and hydrolyzed starch. Especially, it is preferable that it is 1 or more types chosen from the group which consists of glucose, galactose, and fructose.

  Examples of the lower alkyl glycoside, which is a saccharide derivative used as a raw material in the present invention, include those obtained by reacting a saccharide with a lower alcohol in the presence of an acid catalyst. As the lower alcohol, an alcohol having 1 to 5 carbon atoms can be used without particular limitation. For example, a linear or branched saturated alcohol such as methanol, ethanol, propanol, isopropanol, various butanols, various pentanols, and various hexanols. And linear or branched unsaturated alcohols such as allyl alcohol and crotyl alcohol. The saccharide is the same as described above.

As the acid catalyst, known ones can be used without particular limitation as long as they are usually used in a dehydration reaction. Examples thereof include at least one selected from strongly acidic ion exchange resins based on paratoluenesulfonic acid, methanesulfonic acid, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, styrene-divinylbenzene copolymer, and the like. Among these, paratoluenesulfonic acid is preferable from the viewpoint of solubility in the higher alcohol.
The amount of the acid catalyst used is preferably 0.001 to 0.10 mol per mol of the reaction product of saccharide and lower alcohol. If the usage-amount of an acid catalyst exists in this range, both the reaction rate and the hue of the alkylglycoside obtained will become favorable. The amount of the acid catalyst is more preferably 0.002 to 0.08 mol, still more preferably 0.003 to 0.05 mol, per mol of the reaction product of the saccharide and the lower alcohol.

  Further, the higher alcohol or its alkylene oxide adduct used as a raw material in the present invention has the following general formula (I):

Or an alkylene oxide adduct thereof, and a mixture thereof. Here, R represents a hydrocarbon group having 6 to 22 carbon atoms, among which a linear or branched alkyl group, alkenyl group, or alkylphenyl group is preferable, and the carbon number is preferably 8 to 16. A represents an alkanediyl group having 2 to 4 carbon atoms, and an ethylene group is particularly preferable. n has an average value of 0 to 5, preferably 0 to 2, and particularly preferably 0. Preferred examples of the higher alcohol represented in this way include lauryl alcohol, myristyl alcohol, octyl alcohol and the like.
The higher alcohol may be an unreacted higher alcohol recovered from the crude alkyl glycoside mainly in the step (III) described later.

  In the present invention, the amount of the higher alcohol used is preferably in the range of 8 to 25 times mol, more preferably in the range of 9 to 22 times mol, and in the range of 10 to 20 times mol with respect to the saccharide or the lower alkyl glycoside. Further preferred. If it is this range, the production | generation of a high condensate can fully be suppressed and there also exists a technical and economical advantage.

In step (I) of the present invention, nitrogen may be blown in order to efficiently remove by-produced water or lower alcohol. Although the amount of nitrogen blown differs depending on the amount of raw material charged, it cannot be generally stated. For example, it is preferable to blow nitrogen of about 10 to 50 ml / min with respect to the amount of 0.10 mol of sugar.
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 synthesis of the crude alkyl glycoside in the step (I) of the present invention, other reaction conditions and the like are described in known methods such as Japanese Patent Publication No. 47-24532, US Pat. No. 383918, European Patent No. 092355, and the like. Just follow.

Further, before step (II), the crude alkyl glycoside containing impurities such as alkyl glycoside, unreacted higher alcohol and coloring substance obtained in this way is relatively mild so that the alkyl glycoside does not decompose. Under certain conditions, predistillation may be performed to remove a part of the unreacted higher alcohol.
The predistillation may be performed under the conditions of a temperature of 100 to 200 ° C., preferably 100 to 140 ° C., and a degree of reduced pressure of 13.3 Pa to 13.3 kPa, preferably 13.3 Pa to 1.33 kPa. There is no particular limitation.

[Step (II)]
Step (II) of the present invention is a step of adding a hydrocarbon oil to the crude alkyl glycoside to obtain a mixture. The hydrocarbon oil is preferably a saturated or unsaturated linear or branched hydrocarbon compound having 12 to 40 carbon atoms. More specifically, examples of the saturated linear hydrocarbon compound include dodecane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, eicosan, heikosan, docosan, tricosan, tetracosan, pentacosan, hexacosan, heptacosan, octacosan, Compounds such as nanocosane and triacontane can be mentioned.
Examples of saturated branched hydrocarbon compounds include tetramethyloctane, methyldodecane, dimethylundecane, trimethyldecane, hexyldecane, methylpentadecane, dimethyltetradecane, trimethyltridecane, tetramethyldodecane, octyldodecane, decyltetradecane, squalane and the like. The compound of this is mentioned.
Examples of the unsaturated linear or branched hydrocarbon compound include compounds such as dodecene, tetradecene, hexadecene, octadecene, icocene, dococene, tetracocene and squalene.
Among these, from the viewpoints of purification capability and efficiency, saturated linear or branched hydrocarbon compounds are preferred, saturated linear or branched hydrocarbon compounds having 16 to 40 carbon atoms are more preferred, A saturated linear or branched hydrocarbon compound having 20 to 35 carbon atoms is more preferable, and a saturated linear or branched hydrocarbon compound having 25 to 35 carbon atoms is particularly preferable. A hydrocarbon compound having a melting point of 80 ° C. or lower is preferable, and a hydrocarbon compound having a melting point of 30 ° C. or lower is more preferable. Examples of such hydrocarbon oils include eicosan, heikosan, docosan, tricosan, tetracosan, pentacosan, hexacosan, heptacosan, octacosan, nanocosan, triacontane, squalane, etc., among which squalane, eicosan, tricosan, and octacosan. More preferably, it is at least one selected from the group. The effects obtained by using any of squalane, eicosane, tricosane, and octacosane are the same.

  The amount of the hydrocarbon oil added is not particularly limited as long as it does not cause a problem in the distillation operation in step (III) and the separation / layering operation in step (IV) described later. Usually, it is 1 to 80 parts by mass, preferably 10 to 80 parts by mass with respect to 100 parts by mass of alkyl glycoside, and 5 to 50 parts by mass, preferably 5 to 40 parts by mass from the viewpoint of viscosity and layer separation. .

[Step (III)]
Step (III) of the present invention is a step of obtaining an alkyl glycoside by distilling the mixture under reduced pressure. If distillation is performed while blowing a gas such as nitrogen or water vapor as necessary under reduced pressure, the apparatus to be used is not limited. For example, as a distillation column, a metal plate mold for gas-liquid contact, a wire mesh in the column, etc. A column packed with irregular packing such as a Raschig ring or a pole ring, or a rectifying column equipped with a plate such as a perforated plate tray or a bubble bell tray, and a gas-liquid contact section in the tower Any of the flash towers not provided may be used. The distillation operation of the present invention can be carried out continuously, batchwise, or semi-batch.
The degree of vacuum of distillation may be appropriately selected depending on the compound, but is usually 133 Pa to 13.3 kPa, preferably 133 Pa to 2.66 kPa. The temperature condition may be appropriately selected depending on the compound, but is usually 80 to 200 ° C, preferably 100 to 150 ° C.
10-50 mass% is preferable with respect to a mixture, and, as for the quantity of nitrogen, water vapor | steam which blows in in operation of distillation, 15-40 mass% is more preferable.

[Step (IV)]
Process (IV) of this invention is a process of isolate | separating hydrocarbon oil from the alkyl glycoside obtained at process (III) as needed.
Specifically, at normal pressure, the alkylglycoside obtained in step (III) is allowed to cool to an appropriate temperature while standing or stirring, whereby hydrocarbon oil can be separated and separated from the alkylglycoside. it can. The temperature condition may be appropriately selected depending on the compound, but is usually 30 ° C to 100 ° C, preferably 50 ° C to 80 ° C.

[Evaluation of fluidity]
The mixture obtained by adding hydrocarbon oil to the crude alkyl glycoside after preliminary distillation in the distillation step was heated to 135 ° C., and the fluidity of the mixture was evaluated according to the following criteria.
○: The mixture does not adhere to the flask wall, and is dry. ×: The mixture adheres to the flask wall and is sticky.

Example 1
In a four-necked 10 liter stirring tank, 15 moles of lauryl alcohol with respect to anhydrous galactose and 0.5 mole% of paratoluenesulfonic acid monohydrate with respect to anhydrous galactose were added, and the temperature was 115. The dehydration reaction was started under the conditions of ° C and pressure of 5.32 kPa (40 mmHg). At this time, generated water was efficiently removed while nitrogen was blown into the reaction mixture. After confirming that galactose was completely consumed after 5 hours, the pressure was returned to normal pressure, and when the reaction product solution reached 80 ° C., 0.05 g (6.0 g) of a 48 mass% sodium hydroxide aqueous solution was obtained. × 10 ^-4 mol) was added for neutralization to obtain a crude alkyl glycoside containing 88% by mass of unreacted lauryl alcohol. This crude alkyl glycoside was predistilled under conditions of a temperature of 120 ° C. and a pressure of 1.33 kPa (10 mmHg) to obtain a crude alkyl glycoside containing 33.4% by mass of unreacted lauryl alcohol.

  To a mixture obtained by adding 18.7 g of squalane to 168.7 g of this crude alkyl glycoside, 23% by mass of water vapor (temperature 100 ° C., pressure 1.33 kPa) was added under the condition of 0.34 g / min. Distillation was performed under the conditions of a temperature of 135 ° C. and a pressure of 1.33 kPa (10 mmHg). When the obtained alkyl glycoside was measured by gas chromatography, unreacted lauryl alcohol was reduced to 1% by mass. Then, when it left still and cooled at 60 degreeC, squalane (upper layer) and the alkyl glycoside (lower layer) isolate | separated and separated into layers. The squalane (upper layer) was decanted to obtain 127.4 g of an alkyl glycoside containing 6.6% by mass of squalane. The results are shown in Table 1.

Example 2
25% by mass of water vapor (temperature 100 ° C., pressure 1.33 kPa) was 0.34 g / of a mixture obtained by adding 85.7 g of squalane to 200 g of the crude alkyl glycoside obtained in the same manner as in Example 1. Distillation was performed under the conditions of a temperature of 135 ° C. and a pressure of 1.33 kPa (10 mmHg) while adding under the condition of min. When the obtained alkyl glycoside was measured by gas chromatography, unreacted lauryl alcohol was reduced to 0.8% by mass. Then, when it left still and cooled at 60 degreeC, squalane (upper layer) and the alkyl glycoside (lower layer) isolate | separated and separated into layers. The squalane (upper layer) was decanted to obtain 144.8 g of an alkyl glycoside containing 7.2% by mass of squalane. The results are shown in Table 1.

Comparative Example 1
The crude alkylglycoside containing 33.4% by mass of unreacted lauryl alcohol after the predistillation obtained in Example 1 was converted to 0.41 g / min of 23% by mass of water vapor (temperature 100 ° C., pressure 1.33 kPa). Distillation was carried out under the conditions of a temperature of 135 ° C. and a pressure of 1.33 kPa (10 mmHg) while adding under the conditions of the above. The results are shown in Table 1.

Claims (6)

The following steps (I) to (III)
Step (I): a step of obtaining a crude alkyl glycoside by reacting a saccharide or a lower alkyl glycoside with a higher alcohol or an alkylene oxide adduct thereof,
Step (II): adding a hydrocarbon oil to the crude alkyl glycoside to obtain a mixture, and Step (III): step of distilling the mixture under reduced pressure to obtain an alkyl glycoside.
And higher alcohols or alkylene oxide adducts thereof are represented by the following general formula (I):

The manufacturing method of the alkyl glycoside represented by these.
(In the formula, R represents a hydrocarbon group having 6 to 22 carbon atoms, A represents an alkanediyl group having 2 to 4 carbon atoms, and n has an average value of 0 to 5). After step (III), the following step (IV)
Process (IV): The manufacturing method of the alkyl glycoside of Claim 1 including the process of isolate | separating hydrocarbon oil.   The method for producing an alkyl glycoside according to claim 1 or 2, wherein 5 to 50 parts by mass of hydrocarbon oil is added to 100 parts by mass of the crude alkyl glycoside.   The method for producing an alkyl glycoside according to any one of claims 1 to 3, wherein the hydrocarbon oil is a saturated or unsaturated linear or branched hydrocarbon compound having 20 to 35 carbon atoms.   The method for producing an alkyl glycoside according to any one of claims 1 to 3, wherein the hydrocarbon oil is at least one selected from the group consisting of squalane, eicosane, tricosane, and octacosane.   The method for producing an alkyl glycoside according to any one of claims 1 to 5, wherein the saccharide is one or more selected from the group consisting of glucose, galactose, and fructose.