JPS6312071B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for epimerizing aldose (hereinafter abbreviated as epimerization), and specifically relates to a method for epimerizing aldose (hereinafter referred to as epimerization), and more specifically, molybdic acid supported on anion exchange fiber (hereinafter such exchange fiber is referred to as Mo-type ion exchange fiber). This invention relates to a method for epitomizing aldose using aldose (abbreviated) as a catalyst.

Conventionally, the method of epitomizing aldose is as follows:
A method is known in which an aqueous solution of aldose is heated and reacted in the presence of molybdate ions. According to this method, about 25% of D-glucose becomes D-mannose, and about 75% of D-mannose becomes D-glyose. It is said that approximately 43% of D-xylose is converted to lyxose and approximately 33% of D-arabinose is converted to D-ribose (Angew. Chem. 83 [23], 967
(1971); Tietskoslovakia Patent No. 149051).
Among these aldoses, especially D-mannose, D-mannitol can be obtained by hydrogenating it, so the epimerization of D-glucose to D-mannose is an important part of the industrial production method of D-mannitol. It becomes a process. As a method for epitomizing D-glucose, the present inventors first epitomized a D-glucose aqueous solution in the presence of molybdate ions, but at a temperature of 110°C or higher and a low pH value, thereby achieving a concentration of 30% or more. A method for obtaining D-mannose in terms of yield was proposed (Japanese Patent Application Laid-Open No. 77007/1983).

However, in these methods, the molybdate ions added to the aldose aqueous solution must generally be removed from the reaction solution after the epitaxial reaction, and discharging the ions as wastewater causes a pollution problem, so they must be recycled. This resulted in a drawback that the manufacturing process became complicated and impractical. As a method to improve these drawbacks, molybdic acid supported on an anion exchange resin instead of molybdate ions in solution (hereinafter such exchange resin will be abbreviated as Mo-type ion exchange resin).
A method is known in which molybdate ions are used as a catalyst (Japanese Unexamined Patent Publication No. 141802/1983), and according to this method, almost no molybdate ions are mixed into the liquid after the epitaxial reaction, and therefore the removal process of molybdate ions is It has the advantage of being omissible. However, when the present inventors examined this method (hereinafter simply referred to as the conventional method), they found that
However, the following industrial drawbacks were observed.

First, the activity of molybdic acid supported on a Mo-type ion exchange resin as an epitaxial catalyst rapidly decreases with use. That is, if a Mo-type ion-exchange resin is added to an aldose aqueous solution and a heating reaction is performed, the Mo-type ion-exchange resin is recovered from the reaction solution, and this is added to a new aldose aqueous solution and the heating reaction is repeated. The activity of the catalyst decreased rapidly, and the recycling of the catalyst through such recovery was ultimately impractical. Second, even if a Mo-type ion exchange resin with decreased activity is regenerated, the degree of regeneration of the activity is low. For example, even if a Mo-type ion exchange resin whose activity had decreased due to repeated use was treated with an aqueous caustic soda solution, washed with water, and then newly supported with molybdic acid, the degree of regeneration of its catalytic activity was low (Figure 3). reference).

The present inventors conducted various studies in view of the above-mentioned actual situation, and as a result, they were able to solve all the drawbacks of the conventional method by using molybdic acid supported on anion exchange fiber as an epitaxial catalyst.
That is, in the present invention, an aqueous aldose solution is supported on anion exchange fibers using molybdic acid as a catalyst at 70°C.
This is an aldose epitaxialization method characterized by carrying out a heating reaction at a temperature above.

The first advantage of the method of the present invention is that the Mo-type ion exchange fibers used in the method can withstand repeated use. The epimerization reaction according to the method of the present invention may be carried out in batches, but from the viewpoint of efficiency, it is practical to use a continuous method in which the exchanged fibers are packed in a column and the aldose aqueous solution is continuously passed through. case,
In the conventional method using Mo-type ion-exchange resin, the catalytic activity decreases rapidly, whereas when Mo-type ion-exchange fibers are used in this method, the decrease in activity is minimal (see Figures 1 and 2). The second advantage of the method of the present invention is that when Mo-type ion-exchange fibers with reduced activity are treated with alkali and then used as Mo-type ion-exchange fibers again, the activity of molybdic acid as a catalyst is well restored. . As mentioned above, the degree of activity recovery due to regeneration is low in conventional methods, whereas
The activity of the Mo-type ion-exchange fiber obtained using this method is restored to almost the same level as before (see Figure 3). A third advantage of the method of the present invention is that the catalyst activity per resin solid content is high. That is, when comparing the Mo-type ion exchange fiber of this method with the Mo-type ion exchange resin of the conventional method, the former requires about 40% of the latter in terms of solid content to obtain the same activity. As described above, in the end, according to the method of the present invention, the production amount of epimerized aldose per converted solid content of Mo-type ion exchange fiber is greatly improved, and for example, in the epimerization of glucose, the production amount of epimerized aldose can be significantly improved. , and D-mannose production rate 25
% or more of the epitaxial reaction solution was approximately 5.4 times that of the conventional method (see Figures 2 and 3).

Next, the structure of the method of the present invention will be explained in detail. First, the main raw material aldose used in the method of the present invention includes aldoses such as D-xylose, D-glucose, D-galactose, D-mannose, and D-arabinose. and mixtures of these with small amounts of oligomers of these aldoses (for example, starch hydrolysates). The concentration of the aqueous solution during this epitaxial reaction of the main raw material is 40 to 80%, preferably
50% to 70% is good.

The anion exchange group of the anion exchange fiber used to support molybdic acid in the method of the present invention is either a primary, secondary or tertiary amino group or a quaternary ammonium group, or Two or more types. There are various methods for producing anion exchange fibers that can satisfy these conditions. For example, a polymer having at least one type of primary to tertiary amino group (e.g., polyethyleneimine, polyvinylpyridine, etc.) is made into a fiber. A method in which a compound having a primary or secondary amine or an amino group is blended with a polymer capable of forming a fiber, spun, and then crosslinked; A method in which amino groups are introduced into polystyrene fibers, novolac fibers, etc. using the same method as in the case of ion exchange resins; and a method in which polyolefin fibers, etc. are impregnated with an aromatic monovinyl monomer and a crosslinking agent. There are methods of polymerizing the fibers and then introducing amino groups, but the method is not limited to these methods as long as the above conditions are met.

The shape of the anion exchange fiber as shown above is the diameter
It is preferably 200μ or less, preferably 100μ or less, and has an aspect ratio (fiber length/fiber diameter) of 3 to 5,000. When the aspect ratio is close to 1, the activity of molybdic acid in the epitaxial reaction decreases, and the activity decreases particularly with continuous use. Further, if the aspect ratio is too small, the resistance during liquid passage becomes large, which is not preferable. On the other hand, if the aspect ratio becomes extremely large, contact with the liquid will be uneven. A particularly preferred aspect ratio is in the range of 10-3000. The larger the ion exchange capacity of the anion exchange fiber, the more molybdic acid can be supported.
Therefore, it is preferable because the activity as a catalyst becomes high.

In the method of the present invention, in order to support molybdic acid on anion exchange fibers, for example, the anion exchange fibers are packed in a column, passed through an aqueous alkali solution to form a free amine type or OH type, and then molybdate salts such as ammonium salt, sodium salt,
An aqueous solution of potassium salt or the like may be passed therethrough. The temperature of the epimerization reaction in the method of the present invention is 70°C or higher, preferably 80°C or higher.
℃ or higher is preferable; if the temperature is lower than 70℃, the reaction will be slow, and if the temperature is too high, the ion exchange fibers may be decomposed. Preferably the temperature is 140°C or lower.

The method of the present invention will be specifically explained below with further examples.

Example 1 Polyethylene fibers were impregnated with vinylbenzyl chloride and divinylbenzene to polymerize within the fibers, and then tertiary amino groups were introduced to increase the average diameter.
11μ, average aspect ratio 262, ion exchange capacity
Anion exchange fibers having a weight of 2.7 meq/g (dry weight; the same applies hereinafter) were produced, and molybdic acid was supported thereon to obtain Mo-type ion exchange fibers. 10g of this Mo type ion exchange fiber, 150g of D-xylose, 150g of water
The mixture was added to an aqueous solution dissolved in g and stirred at 80° C. for 4 hours to perform an epimerization reaction. The solution obtained by cooling and filtering the reaction-completed solution contains a mixture of α-type and β-type of the raw material sugar and the produced epi-saccharide, so the same solution is directly subjected to gas chromatography using the TMS conversion method. , the peaks overlap, making accurate analysis impossible. Therefore, in this example, the above-mentioned reaction solution was reduced with sodium borohydride to give the corresponding sugar alcohol, which was then acetylated and then subjected to gas chromatography to measure the composition ratio of the acetylated product. The sugar composition of the reaction solution was as follows (the same applies to the following examples).
The results obtained by this method were as follows.

D-xylose 53.3% D-lyxose 44.8% Impurities 1.9% Example 2 An epimerization reaction was carried out in the same manner as in the previous example except that D-arabinose was used as the main raw material. The sugar composition of the obtained reaction solution was as follows.

D-arabinose 67.9% D-ribose 30.6% Impurities 1.5% Example 3 Same as Example 1 except that D-mannose was used as the main raw material, and the epitaxial reaction temperature was 95°C and the reaction time was 2 hours. Epimerization reaction was carried out in the same manner. The sugar composition of the obtained reaction solution was as follows.

D-mannose 38.6% D-glucose 61.4% Example 4 Except for using D-glucose as the main raw material,
The epimerization reaction was carried out in the same manner as in Example 3. The sugar composition of the obtained reaction solution was as follows.

D-glucose 30.2% D-mannose 69.8% Example 5 35 g of Mo-type ion exchange fiber prepared in the same manner as in Example 1 was packed into a jacketed glass tube column with an inner diameter of 2 cm and a length of 60 cm, and kept at 80°C. did. A 50% D-xylose aqueous solution was passed through the top of the column at a rate of 70 ml per hour to carry out a continuous epimerization reaction. After 5 hours, the production rate of D-lyxose based on the raw material D-xylose in the reaction solution discharged from the bottom of the column was 41.2%. Furthermore, sampling was carried out in the same manner every 5 hours to measure the production rate of D-lyxose. The results were as shown in FIG. 1, that is, there was only a slight decrease in the catalytic activity of the Mo type ion exchange fiber used.

Example 6 D-glucose was used as the main raw material, the reaction temperature was 95°C, and the liquid flow rate was 90ml/hour.
A continuous epitaxial reaction was carried out in the same manner as in Example 5. After 5 hours, the production rate of D-mannose based on the raw material D-glucose in the reaction solution discharged from the bottom of the column was 30.2%. Further, sampling was carried out in the same manner every 5 hours to measure the production rate of D-mannose, and the results were as shown in curve A in FIG. 2, that is, there was only a slight decrease in the activity of the Mo type ion exchange fiber used.

Example 7 After passing through the liquid for 35 hours in Example 6, the Mo type ion exchange fiber was washed with water while still in the column, passed through a 5% caustic soda aqueous solution, washed with water, and regenerated through a saturated ammonium molybdate aqueous solution. Thereafter, a 50% D-glucose aqueous solution was passed through this in the same manner as in Example 6. The production rate of D-mannose in the reaction solution discharged from the bottom of the column after 5 hours is
It was 28.8%. Furthermore, the results of measuring the production rate of D-mannose by sampling in the same manner every 5 hours are as shown in curve A in Figure 3, that is, the recovery (increase) of activity due to regeneration of Mo-type ion exchange fibers was good. , and there was only a slight decrease in activity over time.

Comparative Example 1 In contrast to the above, instead of 35 g of Mo type ion exchange fiber in Example 6, styrene divinylbenzene quaternary ammonium anion exchange with a particle size of 0.5 mm (i.e. aspect ratio 1) and an ion exchange capacity of 4.4 meq/g was used. Resin (product name Amberlite A-26; Rohm
A continuous epimerization reaction of D-glucose was carried out in the same manner as in the same example except that 88 g (dry weight) of a Mo-type ion exchange resin supported with molybdic acid was used. The results of sampling every 5 hours and measuring the production rate of D-mannose are as shown in curve B in Figure 2, that is, this
The catalytic activity of the Mo-type ion exchange resin decreased rapidly.

Comparative Example 2 The Mo-type ion exchange resin that had been passed for 35 hours in Comparative Example 1 was regenerated in the same manner as in Example 7, and a 50% D-glucose aqueous solution was passed therethrough. The results of measuring the production rate of D-mannose by sampling every 5 hours are as shown in curve B in Figure 3, that is, the degree of recovery (increase) in activity due to regeneration of the Mo-type ion exchange resin is low, and The activity decreased rapidly over time.

[Brief explanation of the drawing]

FIG. 1 shows a continuous epimerization reaction curve of D-xylose according to the method of the present invention (Example 5) (representing the relationship between the continuous reaction time and the production rate of epimerized sugar in the reaction solution at each time; the same applies hereinafter); Curves A and B in Figure 2
3 are continuous epimerization reaction curves of D-glucose according to the method of the present invention (Example 6) and the conventional method (Comparative Example 1), respectively. Curves A and B in FIG. 7) Continuous epimerization reaction curves of D-glucose according to Example 7) and the conventional method (Comparative Example 2).

Claims (1)

[Claims] 1. A method for epimerizing aldose, which comprises heating an aldose aqueous solution to a temperature of 70° C. or higher using molybdic acid supported on anion exchange fiber as a catalyst. 2. Claim 1, wherein the aldose is one selected from the group consisting of D-xylose, D-glucose, D-galactose, D-mannose, D-arabinose, and mixtures of these aldoses with small amounts of oligomers thereof. Method described. 3. The method according to claim 1 or 2, wherein the concentration of the aldose aqueous solution is 40 to 80%. 4 Claims 1 to 4, wherein the anion exchange group of the anion exchange fiber is at least one selected from the group consisting of primary, secondary, and tertiary amino groups and quaternary ammonium groups. The method described in Section 3. 5. The method according to claims 1 to 4, wherein the anion exchange fiber has a diameter of 200 μm or less and an aspect ratio of 3 to 5,000. 6. The method according to claims 1 to 5, wherein the heating reaction temperature is 80 to 140°C.