JP2000001503A - Production of carboxy polysaccharide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively separate ruthenium from a reaction solution in producing a carboxy polysaccharide by oxidation with a combination of ruthenium with an oxide. SOLUTION: There is provided a process for producing a carboxy polysaccharide by oxidizing it with a combination of a ruthenium compound with an oxidizing agent, which process comprises: reacting the polysaccharide in the presence of reaction additives; adding an oxidizing agent to the reaction mixture after the reaction to bring the ruthenium into a highly oxidized state; and separating the ruthenium by extraction with a water-insoluble organic solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a carboxy polysaccharide or a salt thereof by oxidizing the polysaccharide. The carboxypolysaccharide or salt thereof obtained according to the present invention can be suitably used as a scale adhesion inhibitor, a pigment dispersant, a sizing agent, a concrete admixture, and a detergent builder.

[0002]

2. Description of the Related Art Conventionally, acrylic acid polymers or acrylic acid / maleic acid copolymers have been industrially produced as detergent builders. However, since these synthetic polycarboxylic acids have a vinyl polymer structure that is not common as a chemical structure of a natural polymer, there is a known problem that biodegradability by microorganisms is extremely low. It is expected that polycarboxylic acids produced by oxidative carboxylation of polysaccharides will help solve this problem as biodegradable builders.

For example, Japanese Patent Publication No. 49-1281 discloses a method for oxidizing a polysaccharide using a combination of periodic acid and chlorite or using hypochlorite. It is described that dicarboxystarch obtained by oxidizing the C2 and C3 positions of the unit monosaccharide has a detergent builder function. A method for producing a tricarboxypolysaccharide by oxidizing a polysaccharide is disclosed in JP-B-47-40.
No. 552 and Czechoslovak Patent 235576 disclose a method in which starch is aldehyde-converted with periodate and then oxidized and carboxylated with nitrous oxide. However, the methods described in these publications require the use of expensive periodate and are not industrially suitable.

Japanese Patent Application Laid-Open No. Hei 9-71601 discloses a method of carboxylating starch using a hypochlorite and a reaction pH under basic conditions in the presence of a ruthenium catalyst. Since ruthenium used here is a very expensive transition metal, the loss of ruthenium in the process of producing tricarboxystarch is severely limited.

In Japanese Patent Application Laid-Open No. Hei 9-71601, a precipitate is formed by treating an oxidation reaction product with a reducing agent such as a sulfite and the color tone of a product polycarboxylic acid obtained by filtering the precipitate. However, there is no description of a specific reduction in ruthenium content.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a carboxy polysaccharide by oxidizing a polysaccharide, wherein ruthenium used in combination with an oxidizing agent is simply and effectively removed from a reaction mixture solution. Accordingly, the present invention provides a method for industrially producing a carboxy polysaccharide.

[0007]

Means for Solving the Problems The inventors of the present invention have studied methods for solving the above-mentioned problems, and as a result, have conducted a reaction in the presence of sulfate or phosphate as a reaction additive. It has been found that a transition metal can be effectively removed by adding an oxidizing agent to the mixture and extracting ruthenium with an organic solvent, thereby completing the present invention.

That is, the present invention relates to a method for producing a carboxy polysaccharide by oxidizing a polysaccharide with a combination of a ruthenium compound and an oxidizing agent, wherein the reaction is carried out in the presence of a reaction additive, and then the mixed solution is reacted. The present invention relates to a method for producing a carboxy polysaccharide, which comprises adding an oxidizing agent to make ruthenium highly oxidized, and then extracting and separating ruthenium with a water-insoluble organic solvent.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The polysaccharides used in the present invention are α-linked polysaccharides such as starch, amylose, amylopectin, pectin, protopectin and pectic acid, and β-linked polysaccharides such as cellulose. Starch is preferred because of the ease of reaction. Examples of the starch include corn starch, potato starch, tapioca starch, wheat starch, sweet potato starch, rice starch, and the like. Water-soluble starch obtained by using these as a raw material and having a reduced molecular weight can also be used. Here, these raw materials are used in a concentration of 0.1 to 80% by weight, preferably 1 to 50% by weight in the reaction solution.

The carboxypolysaccharide of the present invention is converted into a carboxyl group or a salt thereof by oxidizing or hydrolyzing the primary alcohol or ester at the C6 position of the monosaccharide pyranose ring constituting the polysaccharide at an average of 10 mol% or more. The C2 and C3 positions of the pyranose ring are cleaved and C2 and C3
A tricarboxy polysaccharide having an average molecular weight of 1,000 to 100,000 and having a structure in which the secondary alcohol is converted to a carboxyl group or a salt thereof oxidized by 10 mol% or more.

The oxidation of the present invention is carried out by a combination of a ruthenium compound and an oxidizing agent. The ruthenium compound includes a ruthenium compound in a high oxidation state. This ruthenium compound in a highly oxidized state can be generated by a ruthenium compound and an oxidizing agent. The ruthenium compound used in the present invention includes ruthenium metal; ruthenium oxide such as ruthenium dioxide and ruthenium tetroxide;
Ruthenates such as sodium ruthenate; ruthenium halides such as ruthenium chloride and ruthenium bromide; ruthenium nitrate; ruthenium sulfate; ruthenium carboxylate such as ruthenium acetate; ammonium hexachlororuthenate, potassium hexachlororuthenate;
Potassium pentachloroaquaruthenate, ammonium pentachloroaquaruthenate, potassium pentachloronitrosylruthenate, hexaammineruthenium chloride, hexaammineruthenium bromide, hexaammineruthenium iodide, nitrosylpentaammineruthenium chloride, hydroxonitrosyltetraamineruthenium nitrate And ruthenium complexes such as ruthenium ethylenediaminetetraacetate and ruthenium dodecacarbonium. The amount of these ruthenium compounds used is
0.0000 per mole of monosaccharide unit constituting polysaccharide raw material
1 to 1.0 times mol, preferably 0.0001 to 0.1
The amount of catalyst is in the range of twice the molar amount.

The oxidizing agent used in combination with the ruthenium compound and the oxidizing agent added to the reaction solution after oxidation include halogen, halogen acid and salts thereof, oxygen,
At least one selected from the group consisting of peracids, hydrogen peroxide, persulfuric acid and salts thereof, and ferricyanide salts is used. Specifically, halogen molecules such as chlorine and bromine;
Halogen oxides such as dichlorine dichloride, chlorine dioxide, dibromine dioxide, and bromine dioxide; perhalic acids and salts thereof such as periodic acid and perchloric acid; halogen acids and salts thereof such as bromate and bromate; Halogenous acids such as bromic acid and chlorous acid and salts thereof; hypohalous acids and salts thereof such as hypobromous acid and hypochlorous acid; peracids such as oxygen, formic acid, peracetic acid and perbenzoic acid; Hydroperoxides such as cumene hydroperoxide and benzyl hydroperoxide; ter
peroxides such as t-butylbenzyl oxide and dibenzoyl oxide; persulfuric acid and salts thereof such as peroxydisulfuric acid; caroic acid; and ferricyanide salts such as potassium ferricyanide and sodium ferricyanide. Among these oxidizing agents, water-soluble halogen acids and salts thereof are preferred. In the oxidation reaction, the amount of these oxidizing agents used is in the range of 1.0 to 10 moles per mole of the raw material,
Preferably, it is 1.5 to 8 times mol.

The reaction solvent of the present invention is usually an aqueous solvent or a mixed solvent of water and a solvent stable to an oxidizing agent. Specific examples of a reaction solvent stable to an oxidizing agent include organic acids such as acetic acid; halogenated carbons such as carbon tetrachloride, chloroform and dichloromethane; methane-based saturated hydrocarbons such as pentane and hexane; and paraffin-based hydrocarbons such as cyclohexane. Is mentioned. Among these solvents, organic acids, halogenated hydrocarbons, and paraffinic saturated hydrocarbons are preferred. When the mixed solvent becomes non-uniform with water, the reaction rate can be increased by sufficiently stirring.

What is added as a reaction additive is a sulfate or phosphate of a Group 1 element. Specifically, it is a salt of lithium, sodium, potassium, rubidium, cesium, and francium. The amount of the reaction additive to be used is 0.01 to 1000 times, preferably 0.1 to 100 times the molar amount of ruthenium. Also, the method of adding
There is no particular limitation, and it is added as a powder at the time of the reaction, or added after being dissolved in water in advance.

In the reaction of the present invention, the oxidizing agent is gradually added while stirring the polysaccharide, the ruthenium compound and the reaction additive to an aqueous solvent or a mixed solvent of water and a solvent stable to the oxidizing agent. At a temperature of 0 to 100 ° C. and a pH of 1 to 13 while producing ruthenium. The reaction mixture contains, in addition to the produced carboxypolysaccharide, sulfates or phosphates, ruthenium compounds, solvents, unreacted trace amounts of raw materials, and the like.

In the separation of ruthenium in the present invention, after the reaction, 1) a first step in which the oxidizing agent is added to the reaction solution to make ruthenium highly oxidized, and 2) a highly oxidized state by an organic solvent insoluble in water. This is performed by a method including a second step of extracting and removing ruthenium. Here, the above steps will be described more specifically.

First Step Ruthenium tetroxide in a highly oxidized state is volatile and oil-soluble, and is known to be well dissolved in non-oxygen-containing solvents such as carbon tetrachloride and chloroform (F). .
S. Martin, J.M. Chem. Soc. , 2564
(1954)). Therefore, in the first step, near the end of the reaction prior to the extraction step in the second step, an oxidizing agent is further added to convert as many ruthenium species as possible into ruthenium tetroxide in a highly oxidized state to increase the extraction efficiency. It is a process for. If this step is omitted and ruthenium tetroxide present near the end of the reaction is extracted in the second extraction step, the extraction efficiency is lowered, which is not preferable. The kind of the oxidizing agent used here may be the same as or different from the oxidizing agent used in the reaction. There is no particular limitation, but the use of the same kind of oxidizing agent is preferable in consideration of the treatment after the reaction.
The amount used is 1.0% based on the amount of ruthenium contained.
It is in the range of 10 to 10 moles, and preferably in the range of 1.2 to 5 moles. The pH at the time of adding the oxidizing agent after the reaction
Can be used as it is at the end of the reaction, but from the viewpoint of the stability of the oxidizing agent to be added and the generated ruthenium tetroxide, the pH is preferably adjusted to 2 to 13, more preferably 4 to 10, and then the oxidizing agent is adjusted. Is desirably added.

Second step This is a step of extracting the ruthenium tetroxide generated in the first step with an organic solvent. The extraction is performed by mixing the aqueous solution of the first step and the organic solvent and then separating the mixture. For the mixing and separation of the aqueous solution and the organic solvent, a known extraction device such as a single-stage or multi-stage mixer settler or an extraction tower can be used. The extraction solvent must be a solvent that is stable to the generated ruthenium tetroxide and insoluble in water. Specifically, halogenated hydrocarbons such as fluorinated carbon such as perfluoroheptane, perfluoropentane and perfluoromethylcyclohexane, chlorinated carbon such as carbon tetrachloride, chloroform and dichloromethane; methane-based saturated such as pentane and hexane hydrocarbon;
Examples include paraffinic hydrocarbons such as cyclohexane and liquid paraffin. Of these solvents, halogenated hydrocarbons and paraffinic saturated hydrocarbons are preferred. These extraction solvents can be used for both purified and unrefined products. In addition, the extraction temperature, the higher the temperature, the faster the extraction speed, but from the physical properties such as the volatility of ruthenium tetroxide,
At normal pressure, the temperature is 0 to 100 ° C, preferably 10 to 80 ° C.

[0019]

The present invention will be described below in detail with reference to examples.
Ruthenium concentration in the resulting tricarboxy starch is IC
The measurement was performed using P (inductively coupled plasma emission spectrometry, 1200 VR type analyzer manufactured by Seiko Instruments Inc.).

Example 1 In a 300 ml round bottom Pyrex flask equipped with a stirrer, thermometer and pump, 25 ml of water, 7.5 g of corn starch (manufactured by Shikishima Starch) and 0.327 g of ruthenium chloride (ruthenium content 43%, ruthenium) 1.39 mmol), 1.98 g of anhydrous sodium sulfate
(13.9 mmol) was added and cooled to 20 ° C. in a cold water bath with stirring. To this mixture, an aqueous solution of 12.9% by weight of sodium hypochlorite in a molar amount of 5 times the amount of starch was added over 3 hours. The pH of the reaction solution was controlled at 9.0 with a 2N aqueous sodium hydroxide solution.

After completion of the reaction, the reaction solution was separated into 70 ml,
2 g of an aqueous solution of 12.9% by weight of sodium hypochlorite and 20 g of n-heptane were added to the reaction mixture, shaken at room temperature (1 minute), centrifuged (2,000 pm, 1 minute), and allowed to stand ( 1 minute), and then dissolved and extracted ruthenium tetroxide
-The heptane layer was separated from the aqueous solution. This extraction operation was performed six times at room temperature. The extract layer was subjected to 2-propanol addition treatment, and then dried under reduced pressure with a rotary evaporator to obtain ruthenium oxide. The aqueous solution after extraction was added with twice the volume of methanol to form a white precipitate. The precipitate was separated by filtration, further dissolved in water, precipitated by adding methanol, and dried under vacuum at 60 ° C. for 5 hours to obtain a product A.

The product A was analyzed by ¹³ C-NMR and IR. As a result, it was found that the primary alcohol at the C6 position of the glucopyranose unit constituting the starting corn starch was 100%.
While being oxidized to mol% carboxyl groups,
The C3 position is cleaved and the secondary alcohol at the C2 and C3 positions is 75
It was a sodium salt of tricarboxystarch oxidized to mol% carboxyl groups. The ruthenium concentration of the product was measured by ICP to be 48 ppm (removal rate 99.7).
%)Met.

Example 2 Instead of anhydrous sodium sulfate, anhydrous potassium sulfate 2.4
The reaction was carried out in the same manner as in Example 1 except that 2 g was used. Separation, extraction, precipitation, and drying after the reaction were performed in the same manner as in Example 1 to obtain a product B. This product is converted to ¹³ C-NM
When analyzed by R and IR, it was the same sodium salt of tricarboxystarch as in Example 1. Product B
The ruthenium concentration in the solution was measured by ICP and found to be 40p
pm (removal rate 99.7%).

Example 3 Trisodium phosphate / 1 instead of anhydrous sodium sulfate
The reaction was carried out in the same manner as in Example 1 except that 5.28 g of dihydrate was used. Separation, extraction, precipitation, and drying after the reaction were performed in the same manner as in Example 1 to obtain a product C. This product
Example 1 was analyzed by ¹³ C-NMR and IR.
And the same sodium salt of tricarboxystarch. The ruthenium concentration in the product C was measured by ICP and found to be 59 ppm (removal rate 99.6%).

Comparative Example 1 A reaction was carried out in the same manner as in Example 1 except that anhydrous sodium sulfate was not used. Separation, extraction, precipitation after reaction,
Drying was performed in the same manner as in Example 1 to obtain a product D. When these products were analyzed by ¹³ C-NMR and IR, they were the same sodium salt of tricarboxystarch as in Example 1. The ruthenium concentration in the product D was measured by ICP and found to be 106 ppm (removal rate 99.2%).

[0026]

According to the present invention, the ruthenium content in the carboxy polysaccharide can be reduced to a low concentration of less than 100 ppm. The method of the present invention is important as a method for industrially producing a purified tricarboxypolysaccharide or a salt thereof by reducing the incorporation of a ruthenium catalyst into a product.

Continued on the front page (72) Inventor Hisashi Sakaiya 6-1-1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas Chemical Co., Ltd. Tokyo Research Laboratory F-term (reference) 4C090 AA05 BA08 BA14 BA18 BA24 BA29 BA50 BC10 CA04 CA09 CA34 CA47 DA21

Claims (5)

[Claims] 1. A method for producing a carboxy polysaccharide by oxidizing a polysaccharide with a combination of a ruthenium compound and an oxidizing agent, wherein the reaction is carried out in the presence of a reaction additive, and then the oxidizing agent is added to the mixed solution after the reaction. Producing ruthenium in a highly oxidized state, and then extracting and separating ruthenium with an organic solvent insoluble in water. 2. The method according to claim 1, wherein the reaction additive is a sulfate or phosphate of a Group 1 element. 3. The method according to claim 1, wherein the oxidizing agent is at least one selected from the group consisting of halogens, halogen acids and salts thereof, oxygen, peracids, peroxides, persulfuric acids and salts thereof, and ferricyanide salts. Manufacturing method. 4. The method according to claim 1, wherein the organic solvent insoluble in water is a saturated hydrocarbon or a halogenated saturated hydrocarbon. 5. The method according to claim 1, wherein the extraction temperature is 0 to 100 ° C. at normal pressure.