JPH10279603A - Production of tricarboxy polysaccharide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a water-soluble tricarboxy polysaccharide having a high carboxyl content and being conveniently usable inexpensively by a simple after- treatment by oxidizing an α-bond polysaccharide (e.g. starch) with a catalytic amount of a high-valence ruthenium formed from a ruthenium compound and an oxidizer such as ozone in an aqueous medium. SOLUTION: The α-bond polysaccharide as a starting material is exemplified by starch, amylose, amylopectin, pectin, protopectin or pectic acid. The starch is desirably corn starch, potato starch, tapioca starch or a water-soluble low- molecular-weight product thereof. It is desirable that these materials are used in a concentration of 5-50 wt.%. The ruthenium compound is exemplified by a metal, an oxide, a hydroxide, a sulfate or a chloride of ruthenium and is used in an amount of 0.0001-0.1 mol, per mol of the starting material. The starting material and a ruthenium compound are mixed in a solvent under agitation, and ozone is added to form a high-valence ruthenium to effect the reaction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for oxidizing an α-linked polysaccharide. More specifically, the present invention relates to a method for producing a tricarboxy polysaccharide by oxidizing an α-linked polysaccharide with a high-valent ruthenium oxide generated by a ruthenium compound and ozone. Tricarboxy polysaccharide obtained by the present invention is a scale adhesion inhibitor, a pigment dispersant,
Used for sizing agents, concrete admixtures, and detergent builders.

[0002]

2. Description of the Related Art Conventionally, various methods for producing a dicarboxy polysaccharide by oxidizing an α-linked polysaccharide have been known. For example, Japanese Patent Publication No. 49-1281 describes a method for oxidizing an α-linked polysaccharide using a combination of periodic acid and chlorite, or using hypochlorite, C
2. It is described that dicarboxy starch obtained by oxidizing the C3 position is an excellent detergent builder.

[0003] JP-A-60-2187 describes a method for producing a dicarboxy polysaccharide by using an α-linked polysaccharide as a combination of sodium hypochlorite, chlorine or periodic acid and a halogen. JP-A-4-175301 describes a method for producing dicarboxypolysaccharides using hypochlorite and / or hypoiodite.

Further, a method for producing a tricarboxy polysaccharide by oxidizing an α-linked polysaccharide is described in, for example, Czechoslovak Patent No. 235576, which discloses that starch is prepared by a combination of periodate and nitrous oxide. A method for making carboxystarch is described. EP 542496 describes a process for producing tricarboxystarch by the combination of a vanadium salt and a nitrite in a concentrated nitric acid, concentrated sulfuric acid solvent.

[0005] However, according to Czechoslovakia Patent No. 235576, a long two-step process, an expensive and complicated oxidizing agent must be used, and the obtained tricarboxy starch is not water-soluble but is inconvenient in use. there were. In addition, in EP 542496, after the reaction, it is not easy to carry out a post treatment of a high-concentration mixed acid, while removing the used metal salt,
There were many problems in terms of disposal, and it was not suitable as an industrial production method.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and comprises the steps of reacting a water-soluble tricarboxypolysaccharide having a high carboxyl group content and convenient for use after the reaction. It is an object of the present invention to provide an industrial method that can be easily and inexpensively manufactured without problems of treatment and generation and removal of by-products.

[0007]

Means for Solving the Problems The present inventors have studied a method for producing a tricarboxypolysaccharide using an α-linked polysaccharide as a raw material, and as a result, have completed the present invention. That is, the present invention uses a high-valent ruthenium oxide produced by a catalytic amount of a ruthenium compound and an oxidizing agent when oxidizing an α-linked polysaccharide in an aqueous solvent or a mixed solvent stable with water and an oxidizing agent. This is a method for easily and inexpensively producing a water-soluble tricarboxyl polysaccharide having a high carboxyl group content and convenient for use without any problem of post-reaction treatment or generation and removal of by-products.

[0008] The tricarboxy polysaccharide referred to in the present invention is:
Specifically, the C of the pyranose ring constituting the α-linked polysaccharide
2. Tricarboxypolysaccharides in which the C3-position is cleaved and the C2 and C3-position secondary alcohols are simultaneously oxidized or hydrolyzed to carboxyl groups by 10 mol% or more and the C6-position primary alcohol or ester by 10 mol% or more. And mixtures thereof.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The raw materials used in the present invention are α-linked polysaccharides, and specifically include starch, amylose, amylopectin, pectin, protopectin and pectic acid. Examples of the starch include corn starch, potato starch, tapioca starch, wheat starch, sweet potato starch, rice starch and the like, and corn starch, potato starch and tapioca starch are particularly preferred. Further, a water-soluble starch obtained by using these as a raw material and reduced in molecular weight is also preferable. These raw materials are used in a concentration of 1 to 80% by weight, preferably 5 to 50% by weight.

The high-valent ruthenium oxide used in the present invention is ruthenium tetroxide having a ruthenium atom of +8 valence. This ruthenium tetroxide is disclosed in Japanese Patent Application No. 9-755.
83, it can be produced by a ruthenium compound and ozone. As the ruthenium compound used in the present invention, ruthenium metal and various ruthenium compounds are used. Specific examples include ruthenium oxides such as ruthenium dioxide; ruthenium hydroxide; ruthenium sulfate; ruthenium halides such as ruthenium chloride and ruthenium bromide; and ruthenium complexes such as ruthenium dodecacarbonium.

Further, a ruthenium metal carrier in which ruthenium metal is carried on various carriers can be used.
Specific examples include ruthenium metal / alumina, ruthenium metal / carbon, ruthenium metal / silica alumina, ruthenium metal / titania, and the like. These ruthenium compounds are used in an amount of 0.00001 to 1 mol, preferably 0.1 mol, per mol of the α-linked polysaccharide as a raw material.
The amount of the catalyst is in the range of 0001 to 0.1 times mol. Here, 1 mol of the α-linked polysaccharide as a raw material refers to glucopyrano-
Or galacturonic acid methyl ester pyranose units.

Ozone, which is an oxidizing agent for a ruthenium compound used in the present invention, may be a method of performing silent discharge in clean dry air or oxygen (ozone generator: ozonizer), a method of irradiating ultraviolet rays to air or oxygen, For electrolysis of diluted sulfuric acid, a reaction between fluorine and water, and a chemical method for oxidizing phosphoric acid. Among these methods, a method using an ozone generator can efficiently and easily obtain a large amount of ozone, and has recently been used on a large scale as a disinfectant for clean drinking water and a wastewater treatment agent. It is most preferable as an industrial method.

The rate of ozone generation varies depending on the reaction conditions, but is usually 0.001 to 100 times mol / min, preferably 0.01 mol, per mol of the ruthenium compound used.
10 to 10 times mol / min.

As the reaction solvent used in the present invention, an aqueous solvent, ruthenium tetroxide as an oxidizing agent, a solvent stable to ozone and oxygen, or a mixed solvent stable to water and an oxidizing agent are usually used. Specifically as a solvent stable to the oxidizing agent,
Organic acids such as acetic acid; halogenated hydrocarbons such as carbon tetrachloride, chloroform and dichloromethane; methane-based saturated hydrocarbons such as pentane and hexane; and cycloparaffinic hydrocarbons such as cyclohexane. Among these solvents, organic acids, halogenated hydrocarbons and paraffin solvents are particularly preferred. In addition, when the mixed solvent becomes non-uniform with water, the reaction rate can be accelerated by sufficiently performing stirring.

[0015] The water-soluble tricarboxy polysaccharide obtained in the present invention can be obtained by converting the pyranose ring of the starting α-linked polysaccharide into C2 and C2.
The 3-position is cleaved and the secondary alcohol at the C2 and C3-positions is oxidized to a carboxyl group in an amount of 10 mol% or more.
It has a polymer structure in which a large number of primary alcohols or esters are oxidized or hydrolyzed to carboxyl groups in an amount of 10 mol% or more and three carboxyl groups hang from the trunk. The molecular weight of this tricarboxy polysaccharide is usually determined by GPC using the polysaccharide as a standard, and the weight average molecular weight is usually 1,000.
It is in the range of 0-100,000.

In the present invention, the product, tricarboxypolysaccharide, is obtained as an aqueous solution. This aqueous solution is desalted by ion exchange membrane, reverse osmosis membrane dialysis, etc., if necessary.
It can be concentrated and used as a scale inhibitor, pigment dispersant, sizing agent, concrete admixture and detergent builder. Further, by adding a lower alcohol or a lower ketone to the aqueous solution of tricarboxypolysaccharide obtained by the reaction, a water-soluble product can be precipitated to obtain a solid.

The method of the present invention is generally carried out by adding a raw material and a catalytic amount of a ruthenium compound to a solvent and gradually adding ozone while stirring to produce a catalytic amount of a highly atomized ruthenium oxide. Reaction temperature is 0-100 ° C, preferably 5-50 ° C
The pH of the reaction solution is 9 or less, preferably 7 or less, more preferably 2 to 5. The time required for the reaction varies depending on the reaction conditions such as the reaction temperature, the pH of the reaction solution, the generation rate of ozone, and the aeration rate. The highly atomized ruthenium oxide is used in the reaction and reduced, and then oxidized again with ozone to produce highly atomized ruthenium oxide.

[0018]

The present invention will be described below in more detail with reference to examples. In the examples, the molecular weight is 0.3 M NaCl, 0.1 M NaH ₂ PO ₄ , 0.33 MK
GPC and H ₂ P0 ₄ aqueous solution as eluent (column: Shodex OH
pack SB-G / Shodex OHpack SB-803HQ 8mm ID x 300mm
L, RI detector) and the weight average molecular weight was measured using the polysaccharide as a sample. In addition, ¹³ CNM was used for the structural analysis of the product.
R and IR were used. The ozone generator used was an ozonizer SG-01A (manufactured by Sumitomo Precision Industries).

Example 1 500 ml equipped with a stirrer, thermometer, pH meter and condenser
300 ml of water, 3 g (0.019 mol) of corn starch and 30 mg of ruthenium dioxide (0.
199 mmol) and add 0.12 g (2.5 mmo) of ozone from oxygen to this solution with an ozone generator while stirring at room temperature (about 20 ° C).
l) The gas generated at a rate of / min was introduced. The pH of the solution immediately before aeration was 5.5 and the reaction was continued until the pH did not change. The reaction time was 3 hours and 30 minutes, and the pH after the reaction was 2.1. After completion of the reaction, the yellow component of ruthenium tetroxide, which is a high valent ruthenium oxide, is replaced with
Extracted three times with 0 ml and removed. The reaction solution after the extraction was adjusted to pH 7 with 1N sodium hydroxide and dried under reduced pressure with an evaporator. Further, vacuum drying was performed at 60 ° C. for 5 hours to obtain 2.8 g of a dry solid. The dried solid is subjected to ¹³ C NMR, IR
The primary alcohol of C6 position in the glucopyranose structure of the raw corn starch was 3
While being oxidized to 0 mol% carboxyl groups,
It was confirmed that tricarboxystarch was formed in which the C2 and C3 positions were cleaved and the secondary alcohols at the C2 and C3 positions were oxidized to 40 mol% carboxyl groups.

The obtained tricarboxy starch is dissolved in water, converted into an acid form with an H-type ion exchange resin, and then mixed with 1 / 20N
As a result, the content of the carboxyl group was 5.4 meq / g. Also GP
The weight average molecular weight measured by C was 3,500.

Example 2 Using the same reaction apparatus as in Example 1, the pH of the reaction solution was adjusted to 4
The reaction was carried out in exactly the same manner as in Example 1 except that the reaction was carried out. The reaction time was 2 hours. After the reaction, the mixture was treated exactly as in Example 1 to obtain 2.4 g of a dry solid.
The structure of the dried solid was analyzed by ¹³ C NMR and IR. As a result, the primary alcohol at the C 6 position of the raw corn starch was oxidized to a carboxyl group at 40 mol%, and at the same time, the C 2 and C 3 positions were cleaved, and C 2 and C 3 It was confirmed that a tricarboxystarch in which the secondary alcohol at the 2nd position was oxidized to 55 mol% carboxyl groups was produced.

Further, the carboxyl group content of tricarboxystarch was determined in exactly the same manner as in Example 1. As a result, the content of the carboxyl group was 6.9 meq / g.
Met. The weight average molecular weight measured by GPC is:
3,300.

Example 3 The reaction and post-treatment were carried out in the same manner as in Example 1 except that the reaction was carried out while maintaining the pH of the reaction solution at 9, and the dried solid material was 1.9.
g was obtained. The resulting dried solid was subjected to structural analysis by ¹³ C NMR and IR. As a result, the primary alcohol at the C 6 position of the raw corn starch was oxidized to a 10 mol% carboxyl group, and simultaneously the C 2 and C 3 positions were cleaved and C 2 ,
It was confirmed that tricarboxystarch in which the secondary alcohol at the C3 position was oxidized to a 20 mol% carboxyl group was formed.

Further, the carboxyl group content of tricarboxystarch was determined in exactly the same manner as in Example 1. As a result, the content of the carboxyl group was 2.8 meq / g.
Met. The weight average molecular weight measured by GPC was 1
It was 2,000.

Example 4 A reaction was carried out in the same manner as in Example 1 except that soluble starch was used as a reaction raw material and ruthenium trisalt was used as a ruthenium compound. The reaction time was 3 hours and 40 minutes. After the reaction, the same treatment as in Example 1 was performed to obtain 2.8 g of a dry solid substance.
I got The structure of the dried solid was analyzed by ¹³ C NMR and IR. As a result, the primary alcohol at the C 6 position of the raw corn starch was oxidized to 35 mol% carboxyl groups, and at the same time, the C 2 and C 3 positions were cleaved and C 2 and C 3 It was confirmed that tricarboxystarch in which the secondary alcohol was oxidized to 43 mol% carboxyl group was formed.

Further, the carboxyl group content of tricarboxystarch was determined in exactly the same manner as in Example 1. As a result, the content of the carboxyl group was 5.8 meq / g. The weight average molecular weight measured by GPC was 3,
800.

Example 5 A reaction and a post-treatment were carried out in the same manner as in Example 1 except that pectin was used as a reaction raw material to obtain 1.5 g of a dry solid.
The resulting dried solid was structurally analyzed by ¹³ C NMR and IR. As a result, the methyl ester group at the C6 position of the galacturonic acid methyl ester pyranose structure of the raw material pectin was 3%.
It was confirmed that C2 and C3 positions were cleaved at the same time as the hydrolysis was performed at 0 mol%, and tricarboxystarch was formed in which the secondary alcohols at C2 and C3 positions were oxidized to 35 mol% carboxyl groups. Was.

Further, the carboxyl group content of tricarboxypectin was determined in exactly the same manner as in Example 1. As a result, the content of the carboxyl group was 5.0 meq / g. The weight average molecular weight measured by GPC was 3,
It was 300.

Comparative Example 1 The same reaction as in Example 1 was carried out without using ruthenium dioxide. After completion of the reaction, the reaction mixture was treated in exactly the same manner as in Example 1, and the obtained dried solid was subjected to structural analysis by ¹³ C NMR and IR. However, formation of tricarboxystarch could not be confirmed.

[0030]

According to the present invention, the post-reaction treatment of a water-soluble tricarboxypolysaccharide having a high carboxyl group content and convenient for use from the α-linked polysaccharide, and the problems of generation and removal of by-products also occur. It can be obtained easily, inexpensively, and is suitable as an industrial method for producing a tricarboxypolysaccharide.

Claims (5)

[Claims] 1. A method for producing a tricarboxy polysaccharide, comprising oxidizing an α-linked polysaccharide with a ruthenium compound and ozone. 2. The process according to claim 1, wherein ozone is supplied to the α-linked polysaccharide in the solvent in the presence of a ruthenium compound. 3. The method according to claim 1, wherein the oxidation is carried out with highly atomized ruthenium oxide generated by a ruthenium compound and ozone. 4. The method according to claim 1, wherein the α-linked polysaccharide is starch, amylose,
The production method according to claim 1, wherein the production method is amylopectin, pectin, protopectin or pectic acid. 5. The method according to claim 1, wherein the ruthenium compound is ruthenium metal, ruthenium metal / carrier, ruthenium dioxide, ruthenium trihalide, ruthenium sulfate or a ruthenium complex.