JPH04224598A - Production of alkylglycoside - Google Patents

Abstract

PURPOSE:To improve productivity by producing a high-quality alkylglycoside excellent in hue and recycling separated unreacted sugar for the reaction. CONSTITUTION:In production of an alkylglycoside using a sugar and a higher alcohol, the sugar is reacted with the higher alcohol using an acid catalyst and unreacted solid sugar is subsequently separated from a reaction mixture containing the unreacted solid sugar. The resultant clean reaction solution is further subjected to an aging reaction using a thin membrane reactor, etc., thus giving the objective alkylglycoside containing <=500ppm dissolved unreacted sugar.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing alkyl glycosides, and more particularly to a method for producing alkyl glycosides with good hue and high production efficiency.

0002

[Prior Art and Problems to be Solved by the Invention] Alkyl glycosides, which are sugar derivative surfactants, are mild surfactants, and even though they are nonionic surfactants, they are themselves stable. In addition to generating bubbles,
It is known to act as a foam stabilizer for other anionic surfactants, and has been attracting attention in recent years.

However, although alkyl glycosides have remarkable properties as new surfactants as described above, their actual production is accompanied by many difficulties.

[0004] Alkyl glycosides are produced by the reaction of sugars and higher alcohols, but the biggest problem is that the hue easily deteriorates due to various operations in the production process.

[0005] For this reason, methods for preventing hue deterioration in the manufacturing process have been studied, and several solutions have been proposed. For example, in the reaction stage of producing an alkyl glycoside by reacting a higher alcohol with a monosaccharide, an acid catalyst composition consisting of an acid catalyst and a reducing agent is used, as described in JP-A-59-139397. Method for carrying out reaction in the presence, European Patent No. 013204
3 and the method of using the acid form of an anionic activator as a catalyst as described in EP 0132
As described in the specification of No. 046, a method of neutralizing with an organic base upon stopping the reaction has been proposed. In addition, in the step of separating the generated alkyl glycoside from the unreacted recovered alcohol by distillation, the color deterioration is particularly significant due to the high viscosity and poor thermal stability of the alkyl glycoside, so a method of adding a viscosity reducer (JP-A-Show) 62
-192396), but the hue of the alkyl glycoside obtained by either method was not satisfactory.

[0006] Furthermore, JP-A-47-16413 proposes that an alkyl glycoside with a good hue can be obtained by contacting the alkyl glycoside production reaction product with a basic anion exchange resin in the form of a hydroxyl group prior to separation. However, in this case, there was a concern that the odor would deteriorate due to the generation of amine odor.

Furthermore, JP-A No. 61-33193 proposes bleaching the alkyl glycoside finally obtained by production using hydrogen peroxide and a sulfur dioxide source, but in this case, the hue is Apart from this, new problems arise such as deterioration in odor and poor storage stability, so it cannot be said to be a fundamental solution.

[0008] Also, in Japanese Patent Application Laid-Open No. 1-290692,
A method has been proposed to improve the color of a glycoside composition by contacting the glycoside composition containing colored humins with hydrogen or a hydrogen source such as sodium borohydride.

[0009] As described above, various methods have been proposed to produce alkyl glycosides with good hue, but the hue of the obtained alkyl glycosides is still unsatisfactory, or there is a problem with deterioration of odor. None of the methods satisfies both color and odor, such as the occurrence of .

[0010] Furthermore, in the method of directly reacting sugar and alcohol, it is difficult to obtain a 100% reaction rate, as a solid condensation product of unreacted sugars is formed due to moisture in the reaction system such as reaction product water. . Moreover, solid unreacted sugars or condensates of solid unreacted sugars can cause quality deterioration such as coloring, so after the reaction is complete, a filter aid is added and discarded after filtration, resulting in a high yield. It was difficult.

Furthermore, according to JP-A-2-237994, a monosaccharide is reacted with an alkyl alcohol, the resulting alkyl glycoside is crystallized by adding a nonpolar solvent, and the alkyl glycoside is separated from the mother liquor. , the non-polar solvent was removed from the mother liquor, and the unreacted sugar and unreacted alcohol were recycled and reused in the reaction, but a satisfactory reaction rate and quality could not be obtained.

0012

[Means for Solving the Problems] As a result of intensive research to solve the above problems, the present inventors have found that the deterioration of the hue of alkyl glycosides is caused by dissolved unreacted sugars, acidic components generated by their decomposition, and furan derivatives. By focusing on the fact that the coloring is mainly caused by substances that cause coloration, by separating the solid unreacted sugar by filtration, it is possible to quickly reduce the dissolved unreacted sugar and obtain high-quality alkyl glycoside. The inventors have discovered that the yield can be improved by reusing the separated solid unreacted sugar, and have completed the present invention.

That is, the present invention, when producing an alkyl glycoside using a sugar and a higher alcohol, uses an acid catalyst to react the sugar and the higher alcohol, and then produces a reaction mixture containing solid unreacted sugar. The present invention provides a method for producing an alkyl glycoside, which comprises further subjecting a clarified reaction solution (hereinafter referred to as clarified reaction solution) obtained by separating solid unreacted sugars from a saccharide to an aging reaction.

According to the method of the present invention, 500% of unreacted sugar dissolved in the alkyl glycoside, which causes coloration, is removed.
By reducing the amount to below ppm, high quality alkyl glycoside can be produced, and the separated solid unreacted sugar can be used again for the reaction.

[0015] Examples of the acid catalyst used in the reaction of sugar and higher alcohol of the present invention include para-toluenesulfonic acid, sulfuric acid, phosphoric acid, and strongly acidic ion exchange resins. The amount of the acid catalyst to be used is preferably 0.001 to 0.10 mol per mol of sugar; if it is less than this range, the reaction rate will drop significantly, and if it exceeds this range, the hue of the alkyl glycoside will not be good.

[0016] The sugars used as raw materials for the production method of the present invention include:
Monosaccharides, oligosaccharides, and polysaccharides are used; examples of the monosaccharides include aldoses such as allose, altrose, glucose, mannose, gulose, idose, galactose, talose, ribose, arabinose, xylose, and lyxose; Examples of oligosaccharides include maltose, lactose, sucrose, and maltotriose, and examples of polysaccharides include hemicellulose, inulin, dextrin, dextran, xylan, starch, and hydrolyzed starch. Desirable among these are reducing sugars having 6 or less carbon atoms.

As the higher alcohol serving as a raw material for the production method of the present invention, linear or branched saturated or unsaturated alcohols having 8 to 22 carbon atoms or alkylene oxide adducts thereof are preferably used.

In the present invention, the charging ratio of raw materials is preferably 2 to 10 moles of higher alcohol per mole of sugar; if it is less than this range, the reaction rate will decrease, and even if it exceeds this range, this There is no advantage from a technical or economic point of view compared to the case within the range.

In the present invention, the reaction between sugar and higher alcohol may be carried out in either a batch or continuous manner, and the reactor may be a batch or continuous stirring tank, a suspension bubble column, or a tubular reactor. etc. are used. The reaction temperature at this time is preferably 70°C to 140°C, more preferably 90°C.
~120°C. When the reaction temperature is higher than 140° C., not only is the hue significantly deteriorated, but also a large amount of condensation products between unreacted sugars is produced, which is unfavorable in terms of quality. On the other hand, below 70°C, the reaction rate becomes extremely slow.

[0020] In the step of separating solid unreacted sugar from the reaction mixture containing solid unreacted sugar obtained in the above reaction, the solid unreacted sugar and the clarified reaction liquid are separated, and the solid unreacted sugar is separated. Either the method used for the next reaction with higher alcohol or the method of continuously obtaining a clarified reaction liquid from the above reaction mixture is possible. The reaction rate when separating solid unreacted sugars is determined by the molar ratio of raw materials charged and the desired average degree of condensation of the alkyl glycoside (the average value of the number of condensations of sugars bonded to one molecule of higher alcohol). Charge molar ratio,
The relationship between the average degree of condensation and the reaction rate is shown in Table 1. Note that the reaction rate in Table 1 refers to the solid glucose consumption rate.

[0021]

[Table 1]

[0022] A filter, a centrifuge, etc. are used in the separation process of solid unreacted sugar, and examples of the filter include a cross-flow filter (using an inorganic or organic porous membrane, the type is a hollow fiber module, a flat (membrane type, etc.), pressure filters, vacuum filters, etc., but cross-flow filters are particularly preferred in consideration of the compressibility of the cake. Further, examples of the centrifugal separator include a decanter type, a separating plate type, and a basket type.

In the present invention, the aging reaction of the clarified reaction solution can be carried out either batchwise or continuously. The aging reaction is preferably carried out in a thin film state, and examples of the thin film reactor used include a falling film reactor, a rising film reactor, a wiped film evaporator, and a drum evaporator. The film thickness varies depending on the device, but is 5 mm or less, preferably 2 mm or less.

[0024] The use of the thin film reactor as described above has the following advantages. 1) Since the aging reaction is a dehydration rate-limiting reaction, by using a thin film reactor with high dehydration efficiency (evaporation efficiency),
Reaction time can be shortened. 2) Thin film reactors have good heat transfer efficiency, small thermal history, and can suppress coloring due to heat.

The temperature of the aging reaction is preferably 60 to 130°C, more preferably 70 to 110°C. If the reaction temperature is higher than 130° C., not only will the hue deteriorate significantly, but also the average degree of condensation of the alkyl glycoside will increase, making it difficult to obtain a product of desired quality. On the other hand, 6
If the temperature is below 0°C, the reaction rate will be slow.

[0026]

EXAMPLES The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples.

Example 1 800.2 g (5 mol) of n-decyl alcohol, 180.1 g (1 mol) of anhydrous glucose, and 0.67 g (3.5 x 10-3 mol) of para-toluenesulfonic acid.
) in a 2 liter stirring tank at a temperature of 110°C and an internal pressure of 40°C.
Dehydration reaction was performed at mmHg. At this time, in order to efficiently remove the water produced by the reaction, 200 m of nitrogen was added to the reaction mixture.
It was blown at l/min. After heating and reaction for 6 hours, the reaction rate reached 93.8%. This reaction mixture was mixed with a pore size of 1
．． Filtration was performed using a cross-flow filter using an 8 μm ceramic porous membrane. The obtained reaction filtrate was
In a falling film reactor with a diameter of 5 mm and a tube length of 1000 mm, the circulation flow rate was 1.0 l/min, the temperature was 90°C, and the system pressure was 4.
The aging reaction was carried out for 2 hours at 0 mmHg. After the reaction was completed, the reduced pressure was released and the mixture was neutralized with 0.12 g of NaOH.
275 g of alkyl glucoside and 70 g of unreacted n-decyl alcohol were distilled at 160°C and 0.5 mmHg.
5g was separated. The obtained alkyl glucoside was dissolved in water to prepare a 35% aqueous solution, and the hue was measured.

Example 2 n-decyl alcohol 104.3 kg (652 mol
), anhydroglucose 58.7 kg (326 mol) and para-toluenesulfonic acid 0.22 kg (1.14 mol)
1) was subjected to a dehydration reaction in a 200 liter stirring tank at a temperature of 100° C. and an internal pressure of 40 mmHg. At this time, nitrogen is added to the reaction mixture in order to efficiently remove the water produced by the reaction.
It was blown in at a rate of 300 l/min. After heating and reaction for 6 hours, the reaction rate reached 40%. At that point, 1200k
Filtration circulation was started at g/Hr (the stirring tank is equipped with a circulation line equipped with a cross-flow filter. The separation membrane of the cross-flow filter has a pore size of 1.8 μm).
A ceramic porous membrane with a diameter of 0.2 m is used, and the filtration area is 0.2
m2). A clear filtrate was obtained at 26.7 kg/Hr.

On the other hand, 22.5k n-decyl alcohol
n-decyl alcohol, anhydrous glucose, alkyl glucoside, and para-toluenesulfonic acid in the stirring tank. The concentration of was kept constant. The obtained filtrate was stored in a 100 liter relay tank, and part of it was circulated in a falling film reactor with an inner diameter of 43 mm and a tube length of 4 m at a flow rate of 360 kg/
The aging reaction was carried out for 1 hour at a temperature of 90° C. and an internal pressure of 40 mmHg. At that point, 26.7 kg/H from the relay tank
The filtrate was started to be fed to the falling film reactor at r. On the other hand, the reaction solution was extracted from the falling film reactor at a rate of 15.7 kg/Hr, neutralized by adding NaOH at a rate of 0.004 kg/Hr, and then distilled at 160°C and 0.5 mmHg to remove any unreacted alkyl glucosides. N-decyl alcohol was separated and alkyl glucoside was obtained at 7.9 kg/Hr. Next, the obtained alkyl glucoside was dissolved in water, and 35
% aqueous solution was prepared and the hue was measured.

Example 3 The aging reaction in Example 1 was carried out in a stirring tank.
Alkyl glucoside was obtained in the same manner as in Example 1. The reaction conditions are the same as in Example 1.

Comparative Example 1 An alkyl glucoside was obtained in the same manner as in Example 1, except that filtration was not performed and the aging reaction was carried out in a stirring tank. The reaction conditions are the same as in Example 1.

Amount of unreacted dissolved sugar at the start of the ripening reaction, hue of the reaction solution, amount of unreacted dissolved sugar after the ripening reaction, hue of the reaction solution, and unreacted n in Examples 1 to 3 and Comparative Example 1 −
Table 2 shows the results of evaluating the hue and odor of the 35% alkyl glucoside aqueous solution after removing decyl alcohol.

[0033]

[Table 2]

As is clear from Table 2, unreacted glucose (solid) is separated by filtration from the reaction mixture obtained by the reaction of sugar and higher alcohol, and the resulting filtrate is subjected to an aging reaction, so that it is not separated by filtration. An alkyl glucoside with a better hue than that obtained by ripening was obtained. In addition, by reusing the separated unreacted glucose (solid), the yield based on glucose in the second and subsequent reactions is approximately
It has reached 100%.

[0035]

Effects of the Invention The method of the present invention has the following effects.

[0036] ■ If the ripening reaction is carried out in the state of the filtrate obtained by separating solid unreacted sugar by filtration, it will cause coloring more than if the ripening reaction is carried out in a state containing solid unreacted sugar. , the rate of decline of dissolved unreacted sugars becomes 4-5 times faster. The remaining amount of dissolved unreacted sugar is at least 500 ppm or less,
It is necessary to reduce it preferably to 100 ppm or less,
When a ripening reaction is carried out in the state of the filtrate obtained by separating solid unreacted sugar by filtration, 500 p of dissolved unreacted sugar can be dissolved in a short time.
It is possible to reduce the amount to below pm. Furthermore, by shortening the time for the aging reaction, coloring during the reaction can be suppressed.

■ Since solid unreacted sugar can be reused, filtration can be carried out at a low reaction rate. That is, due to the relationship shown in Table 1 above, the molar ratio of charging can be reduced, resulting in improved productivity.

■ Since solid unreacted sugar does not leave the system (is reused), the reaction yield increases by 1 as the number of reuses increases.
Approaching 00%.

[0039]

Claims (3)

[Claims] Claim 1: When producing an alkyl glycoside using a sugar and a higher alcohol, after the sugar and the higher alcohol are reacted using an acid catalyst, the solid unreacted sugar is extracted from the reaction mixture containing the solid unreacted sugar. A method for producing an alkyl glycoside, which comprises further subjecting a clarified reaction solution obtained by separating reaction sugars to a ripening reaction. 2. The production method according to claim 1, wherein the amount of unreacted sugar dissolved in the alkyl glycoside obtained by the aging reaction is 500 ppm or less. 3. The manufacturing method according to claim 1, wherein the aging reaction is carried out in a thin film state.