JP2995839B2 - Method for producing alkyl glycoside - Google Patents

Description

The present invention relates to a method for producing an alkyl glycoside having a low degree of sugar polymerization.

Alkyl glycosides have surface activity and are useful as raw materials for detergents.

[Conventional technology]

Examples of the method for producing an alkyl glycoside having surface activity include a method of directly reacting a sugar with an excess of a higher alcohol in the presence of an acid catalyst (direct method), and a method of reacting a sugar with a lower alcohol or glycol to obtain a lower alcohol. A method of acetal exchange of an alkyl glycoside with a higher alcohol (acetal crossing) is typical.

In the acetal exchange method, the control of the reaction is easier and a light-colored alkyl glycoside can be obtained as compared with the direct reaction method, but the operation is complicated and the cost such as equipment cost is increased.

As the lower alcohol used in the acetal exchange method, butanol is typical (JP-A-48-1071).
No. 6, No. 58-194901, No. 64-47796).

However, in order to produce an alkyl glycoside having a low degree of sugar polymerization, a complicated reaction control operation was required.

As a method for adjusting the sugar polymerization degree in an acetal exchange method using a lower alcohol such as butanol, for example,
JP-B-47-24532 discloses a method of changing the ratio of sugar to higher alcohol and the amount of an acid catalyst.
JP-292789 discloses a method for changing the amount of an acid catalyst for a higher alcohol.

In order to obtain an alkyl glycoside having surface activity, a raw material higher alcohol having a carbon number of 8 to 20 is used. Such an alkyl glycoside has a higher viscosity as the degree of sugar polymerization increases. . When the excess higher alcohol is distilled off from the reaction product after the reaction is completed, if the reaction product contains an alkylglycoside with a high degree of sugar polymerization, the viscosity of the reaction product increases, making it difficult to separate by distillation. Is generated.

As a method for separating the higher alcohol by distillation, for example, in Japanese Patent Application Laid-Open No. 58-194902, a method in which a thin film evaporator is used under specific conditions, and in Japanese Patent Application Laid-Open No. 62-192396, A method is disclosed in which a high boiling polar solvent such as ethoxylate is added as a viscosity reducing additive.

[Problems to be solved by the invention]

An object of the present invention is to provide a method for producing an alkylglycoside having a low degree of sugar polymerization in an industrially advantageous manner, in a short time, without requiring a complicated reaction operation or addition of a high-boiling solvent, etc. That is.

[Means for solving the problem]

The present invention provides a method for producing an alkyl glycoside, comprising reacting a saccharide with a cyclic saturated alkyl alcohol in the presence of an acid catalyst, and performing an acetal exchange reaction by adding a chain alcohol to the obtained reaction mixture, or A method for producing an alkyl glycoside by reacting a sugar with a chain alcohol in the presence of an acid catalyst, wherein a cyclic saturated alkyl alcohol is coexistent.

As the saccharide used in the present invention, a monosaccharide is preferable.
Specific examples of the monosaccharide include hexoses such as glucose, mannose, galactose, talose, fructose, sorbose, tagatose, and psicose, and pentoses such as arabinose, xylose, ribose, lyxose, ribulose, and xylulose. Among them, glucose is preferred because of its availability and low cost.

Examples of the cyclic saturated alkyl alcohol include those having 5 to 8 carbon atoms.
Are preferred, specifically, cyclopentanol,
Cyclohexanol, cycloheptanol, cyclooctanol and the like can be mentioned. Among them, cyclohexanol is preferred because of its availability and low cost.

The ratio of sugar to cyclic saturated alkyl alcohol is sugar: cyclic saturated alcohol = 1: 1 to 1:20, preferably 1: 3 to 1:10
It is a molar ratio.

Examples of the acid catalyst used in the method of the present invention include strong mineral acids such as hydrochloric acid, hydrofluoric acid, phosphoric acid, sulfuric acid, and mixtures thereof, and strong acids such as phosphonic acid or sulfonic acid of alkyl, alkylaryl or aryl compounds. Organic acids may be mentioned. Representative examples of strong organic acids include sulfonic or phosphonic acids having a methyl, ethyl, butyl, propyl or amyl group, phenylsulfonic acid, phenylphosphonic acid, paratoluenesulfonic acid, paratoluenephosphonic acid and mixtures thereof. .

The amount of the acid catalyst used is 1 to 100 milliequivalents per mole of sugar,
Preferably, it is in the range of 5 to 30 meq. When the amount of the acid catalyst is small, the reaction rate is low, and when the amount is too large, turbidity is liable to be produced in the obtained aqueous alkyl glycoside solution.

The reaction between the sugar and the cyclic saturated alkyl alcohol is generally performed in the range of 90 to 150 ° C. in the presence of an acid catalyst, and is achieved by azeotropically producing water with the cyclic saturated alkyl alcohol and removing the water out of the reaction system. . The vapor can be cooled in a condenser to separate the aqueous phase and the cyclic saturated alkyl alcohol phase, and the cyclic saturated alkyl alcohol phase can be refluxed.

The lower the reaction temperature, the lower the yield of the alkylglycoside having a low degree of sugar polymerization, but the lower the reaction rate. Therefore, the lower limit is 90 ° C.

Sugars may be supplied all at once into a saturated cyclic alcohol containing an acid catalyst, but continuous or intermittent supply provides an alkyl glycoside with a low degree of sugar polymerization.

One of the reaction methods for obtaining an alkyl glycoside of a chain alcohol is to add a chain alcohol to a reaction mixture obtained by reacting a sugar with a cyclic saturated alcohol in the presence of an acid catalyst, and carry out an acetal exchange reaction. How to do it.

Chain alcohols used to produce the alkyl glycosides of chain alcohols include natural alcohols,
Ziegler alcohol, oxo alcohol and the like are used. In order to obtain an alkyl glycoside having surface activity, a primary alcohol having a linear or branched chain having 8 to 20 carbon atoms is preferable. Specifically, octyl alcohol,
Nonyl alcohol, decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol,
Tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, nonadecyl alcohol, eicosyl alcohol or a mixture thereof. Among them, a chain alcohol having 10 to 14 carbon atoms is preferable.

The ratio of sugar (total amount added to the reaction system) to chain alcohol is sugar: alcohol = 1: 1 to 1:10, preferably 1: 2 to
It is in the range of 1: 5 (molar ratio).

When the reaction between the sugar and the cyclic saturated alcohol is completed, the distillation of the reaction product water stops, and the reaction mixture becomes transparent. By taking it out,
The acetal exchange reaction proceeds.

Reaction temperatures are generally in the range from 90 to 150 ° C. If the temperature is too low, the reaction rate will be slow, but from the viewpoint of hue, the lower the temperature, the better. The reaction pressure is reduced to 5 to 100 Torr in order to quickly and surely take the cyclic saturated alkyl alcohol out of the system.

As another method for obtaining an alkyl glycoside of a chain alcohol, there is a method in which a sugar is added and reacted in the coexistence of a cyclic saturated alkyl alcohol and a chain alcohol. According to this method, an alkyl glycoside having a low degree of sugar polymerization can be obtained.

In this method, a cyclic saturated alcohol, a chain alcohol and an acid catalyst are mixed and maintained at 90 to 150 ° C., and a sugar is added thereto and reacted. The ratios of sugar to chain alcohol and sugar to cyclic saturated alcohol are the same as those described above. In addition, the ratio of cyclic saturated alcohol to chain alcohol is such that cyclic saturated alcohol: chain alcohol = 10: 1 to 1:
5, preferably 5: 1 to 1: 2 (molar ratio) The sugar may be supplied in its entirety at once, but is preferably supplied continuously or intermittently. The water formed according to the reaction is separated off along with the azeotropic cyclic saturated alcohol. The cyclic saturated alcohol can be separated from water and returned to the reaction system. At the time when the distillation of the produced water is completed, that is, at the time when the reaction with the sugar is completed, there are cyclic alkyl glycosides, higher alkyl glycosides, unreacted chain alcohols, cyclic saturated alcohols, and the like.

After completion of the reaction with the sugar, the cyclic saturated alcohol is taken out of the reaction system under reduced pressure, whereby the acetal exchange reaction proceeds. The reaction conditions in this case are the same as in the above method.

 After the completion of the reaction, the acid catalyst in the reaction product is neutralized.

In the present invention, as an alkaline compound suitable as a neutralizing agent for an acid catalyst, an alkali metal or alkaline earth metal hydroxide, carbonate, lower alcoholate and the like are used. Among them, preferred are alkaline earth metal hydroxides such as magnesium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide.Especially, when magnesium hydroxide is used, the hue of the obtained alkyl glycoside is pale. Therefore, the decolorization effect is the best and preferable.

The amount of the alkaline compound used is 1 to 2 with respect to the acid catalyst.
Equivalents, preferably in the range of 1.1 to 1.6 equivalents. If the amount of the alkaline compound used is small, the neutralization is not complete,
On the other hand, if the amount is too large, the turbidity of the aqueous alkyl glycoside solution increases.

The neutralization temperature is in the range of room temperature to the glycosidation reaction temperature, but is preferably a high temperature in order to complete the neutralization in a short time and reliably, and more preferably in the range of 90 ° C to the glycosidation reaction temperature.

The time required for the neutralization varies depending on the amount of the neutralizing agent, the temperature, the efficiency of the stirring device, and the like, but is generally in the range of 10 to 60 minutes.

After neutralization, excess alcohol is separated by distillation under reduced pressure or the like to obtain the desired alkyl glycoside.

Examples of the chain alkyl glycoside obtained in the present invention include:
Those represented by the following general formula are preferred.

RO [X] _n H (wherein, R is a chain alkyl group having 8 to 20 carbon atoms, X is a pentose or hexose residue, n is an integer of 1 to 20, and the average value n is [Effect of the Invention] According to the method of the present invention, an alkyl glycoside having a low degree of sugar polymerization can be easily produced in a short time under mild conditions. Since an unnecessary apparatus, condition, or additive for reducing viscosity is not required, an alkyl glycoside suitable as a detergent can be industrially advantageously produced.

〔Example〕

 Hereinafter, the present invention will be described in more detail with reference to Examples.

The higher alcohol used in the following experiments was obtained by hydroformylation of an alpha olefin having 10 carbon atoms and obtained by hydroformylation.
Is a so-called oxo alcohol having a linear chain ratio of 72%.

<Example 1> cyclohexanol 150g, C ₁₁ higher alcohol 150g
(0.872 mol) was charged into a 0.5 flask equipped with a stirrer, thermometer, dropping funnel and separatory reflux tube, and 0.5 g (2.63 meq) of paratoluenesulfonic acid monohydrate was added as a catalyst.

The flask was placed in an oil bath adjusted to 125 ° C., and cyclohexanol was refluxed under reduced pressure while stirring.

Add 7.5 g (0.042 mol) of anhydrous glucose through a dropping funnel to 30
The solution was dropped four times (30 g in total) at minute intervals. During this time, the water produced as a by-product was separated from the cyclohexanol in the separatory reflux tube and removed from the system.

After the reaction liquid became transparent, the temperature of the oil bath was lowered to 110 ° C., and the pressure was gradually lowered to distill cyclohexanol, thereby performing an acetal exchange reaction. Distillation was continued until all the charged cyclohexanol was recovered. During this time, it takes about 2 hours to gradually increase the pressure from 100 Torr to 10 Tor.
lowered to r.

After the temperature of the oil bath was lowered to 90 ° C., 0.092 g of magnesium hydroxide was added as a neutralizing agent, and the mixture was stirred for 1 hour.

Next, after raising the oil bath temperature to 150 ° C, the pressure was increased to 2
C ₁₁ higher alcohol excess was distilled to below 1 wt% in the following vacuum rr. The time required for distillation was 2 hours.

A part of the obtained alkyl glycoside was collected, and the ratio of the saccharide unit to the alkyl group unit (the same applies hereinafter) was measured by an NMR analyzer, and it was 1.2.

<Comparative Example 1> The same operation as in Example 1 was performed except that n-butanol was used instead of cyclohexanol. Was 1.5.

<Example 2> The same operation as in Example 1 was performed except that the entire amount (30 g) of anhydrous glucose was added at one time, and the reaction time was changed to 1.5 hours. Was 1.3.

Example 3 The reaction temperature between anhydrous glucose and cyclohexanol was set to 11
The same operation as in Example 2 was performed except that the temperature was 0 ° C. and the reaction time was 4 hours. Was 1.0.

The addition of <Example 4> C ₁₁ higher alcohol, except that the reaction of anhydrous glucose and cyclohexanol (4 hours reaction time) was performed after the completion of operation was conducted in the same manner as in Example 2. Is
1.5.

<Comparative Example 2> The same operation as in Example 4 was performed except that n-butanol was used instead of cyclohexanol. Was 1.9.

<Example 5> The same operation as in Example 3 was performed except that cyclopentanol was used instead of cyclohexanol and the reaction time was changed to 4 hours. Was 1.0.

Claims (3)

(57) [Claims] 1. A process for producing an alkyl glycoside, comprising reacting a saccharide with a cyclic saturated alkyl alcohol in the presence of an acid catalyst, adding a chain alcohol to the resulting reaction mixture, and performing an acetal exchange reaction. 2. A method for producing an alkyl glycoside by reacting a sugar with a chain alcohol in the presence of an acid catalyst, wherein the method comprises producing a cyclic saturated alkyl alcohol. 3. The production method according to claim 1, wherein the cyclic saturated alkyl alcohol is cyclohexanol.