JPH09316103A - Manufacture of polycarboxylic acid type polysaccharide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polycarboxylic acid type polysaccharide without producing concomitantly a halide salt by bringing a polysaccharide in contact with hydrogen peroxide in the presence of a catalyst. SOLUTION: A polysaccharide and hydrogen peroxide in an amount of 0.05 to 5mol per mol of the glucopyranose units constituting the polysaccharide are brought to come in contact with each other at a reaction temperature of 30 to 150 deg.C for a reaction time of 10min to 24 hours in the presence of a heteropolyacid as a catalyst to effect the oxidation reaction, preferably followed by oxidation with highly concentrated oxygen or molecular oxygen such as air, to obtain a polycarboxylic acid type polysaccharide wherein the -CH2 OH in the 6position and one or both of the -CH(OH)- in the 2-position and the 3position of the pyranose rings have been oxidized to carboxyl groups.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polycarboxylic acid type polysaccharide. More specifically, the present invention relates to a method for producing a polycarboxylic acid type polysaccharide by oxidizing a polysaccharide. The polycarboxylic acid type polysaccharide obtained by the present invention is a scale adhesion preventing agent, a pigment dispersant, a sizing agent,
It can be used as a concrete admixture or a detergent builder.

[0002]

2. Description of the Related Art Various methods for producing polycarboxylic acid-type polysaccharides by oxidizing polysaccharides are conventionally known. For example, Japanese Patent Publication No. Sho 49-1281 describes a method of oxidizing a polysaccharide using a combination of periodate and chlorite, or hypochlorite. It is described that the polycarboxylic acid type starch obtained by oxidizing the 3-position shows excellent detergency builder performance. JP-A-60-218
No. 47 describes a method for oxidizing a polysaccharide using sodium hypochlorite or chlorine, or a combination of periodic acid and halogen. JP-A-60-226502 describes a method for oxidizing a polysaccharide by reacting hypochlorite at 25 to 40 ° C. JP-A-4-175301 describes a method for oxidizing polysaccharides using hypobromite and / or hypoiodite.

[0003] However, these methods have a problem in industrial production in that relatively expensive oxidizing agents must be used.

Further, these methods inevitably produce a considerable amount of halide salt as a by-product, but it is necessary to remove the halide salt almost completely depending on the use.

Japanese Patent Application Laid-Open No. 60-225697 discloses a method for oxidizing starch using hydrogen peroxide, in which the reaction is carried out at 80 ° C. or higher in the presence of iron ions.
Japanese Patent Publication No. 6-15543 describes a method for producing a carboxyl group in the hemiacetal portion of a saccharide by a reaction of oxidizing the hemiacetal of a saccharide in the presence of a heteropolyacid.

Although these methods do not involve the by-product of a halide salt, they are insufficient for producing a polycarboxylic acid type polysaccharide having a high carboxyl group content, which is the object of the present invention, in a high yield. .

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved industrial method for producing a polycarboxylic acid type polysaccharide having a high carboxyl group content.

[0008]

Means for Solving the Problems The present inventors have conducted intensive studies on a method for producing a polycarboxylic acid type polysaccharide using a polysaccharide as a raw material, and as a result, have completed the present invention.

That is, the present invention relates to a method of contacting a polysaccharide with hydrogen peroxide in the presence of a heteropolyacid as a catalyst to carry out an oxidation reaction. The present invention preferably relates to a method of first oxidizing a polysaccharide by contacting it with hydrogen peroxide in the presence of a heteropolyacid and then contacting it with oxygen.

[0010] The polycarboxylic acid-type polysaccharide referred to in the present invention refers to -C at the 6-position of the glucopyranose ring constituting the polysaccharide.
It is a polycarboxylic acid type polysaccharide in which H2 OH, -CH (OH)-at the 2,3-position or both are oxidized to a carboxyl group.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is a method of bringing a polysaccharide and hydrogen peroxide into contact with each other in the presence of a heteropolyacid as a catalyst to carry out an oxidation reaction. The present invention is preferably a method of first oxidizing a polysaccharide by contacting it with hydrogen peroxide in the presence of a heteropolyacid, and then contacting it with oxygen.

In the present invention, when a polysaccharide is oxidized with hydrogen peroxide in the presence of a heteropolyacid, hydrogen peroxide is contained in the glucopyranose unit constituting the polysaccharide in an amount of from 0.05 to 0.05.
A 5-fold molar amount, preferably a 1- to 4-fold molar amount is used, the reaction temperature is 30 to 150 ° C, preferably 60 to 100 ° C, and the reaction time is 10 minutes to
24 hours. As the hydrogen peroxide, not only an industrially produced hydrogen peroxide aqueous solution but also one that generates hydrogen peroxide in water can be used.

In the present invention, preferably, a reaction mixture containing a catalyst obtained by oxidizing a polysaccharide with hydrogen peroxide is obtained, and further this is contacted with molecular oxygen. The reaction temperature for the oxidation with oxygen is generally 30 to 150 ° C, preferably 60 to 120 ° C, and the reaction time is 5 minutes to 24 hours, preferably 10 minutes to 8 hours. As the oxygen source used in the subsequent reaction in the present invention, high-concentration oxygen, air, molecular oxygen such as a mixed gas of oxygen and nitrogen can be used, but it is preferably produced by the PSA method or the liquefaction method. High concentration oxygen. Oxygen generated by decomposition of hydrogen peroxide can also be used. The partial pressure of oxygen in the oxidation reaction with oxygen is usually selected from the range of 0.2 to 100 kgf / cm2G, preferably
Pressurized oxygen of 1 kgf / cm2 · G or more and less than 10 kgf / cm2 · G is more preferable for industrial implementation.

The polysaccharide as a raw material in the present invention includes starch, (hemi) cellulose, inulin, dextran, dextrin, alginic acid and xylan, of which starch is particularly preferable. Examples of the starch include corn starch, potato starch, tapioca starch, wheat starch, sweet potato starch, and rice starch, and corn starch is particularly preferred. A soluble starch obtained by using these as a raw material and having increased water solubility is also preferable.

The heteropolyacid used as a catalyst in the present invention comprises at least one known heteropolyacid or heteropolyacid salt. Preferred heteropoly acids are
Heteroatoms are phosphorus, arsenic, silicon, boron or germanium and polyatoms are molybdenum, tungsten, niobium,
A heteropolyacid having a Keggin structure or a Dawson structure, which is vanadium or a mixture thereof.

For example, phosphomolybdic acid, arsenic molybdic acid, silicomolybdic acid, germanomolybdic acid, boromolybdic acid, phosphotungstic acid, arsenic tungstic acid, silicotungstic acid, germanotungstic acid, borotungstic acid, phosphovanadic acid, Arsenic vanadic acid,
Civanadic acid, germanovanadic acid, borovanadic acid, phosphoniobate, arsenic niobate, cinniobate, germanoniobate, booniobate and their lithium salts, sodium salts, potassium salts, rubidium salts, cesium salts, beryllium salts, magnesium salts. , Calcium salt,
Strontium salt, barium salt, copper salt, silver salt, zinc salt,
Metal salts such as cadmium salts, iron salts, cobalt salts, nickel salts, ruthenium salts, rhodium salts, palladium salts, platinum salts and ammonium salts, tertiary amine salts, organic base salts such as pyridine salts, and phosphomolybdic acid. And phosphotungstic acid are preferred because of their high activity.

The oxidation reaction in the present invention is preferably carried out in the pH range of 1-9, more preferably in the range of 2-5. In the present invention, the polycarboxylic acid-type polysaccharide is obtained as an aqueous solution. If necessary, the resulting polycarboxylic acid-type polysaccharide aqueous solution is subjected to ion exchange resin treatment or concentration,
It can be used as a scale adhesion inhibitor, a pigment dispersant, a sizing agent, a concrete admixture, or a detergent builder. Further, a solid may be obtained by adding a lower alcohol or a lower ketone.

[0018]

EXAMPLES The present invention will be described in more detail with reference to examples. In this example, the molecular weight is (NaCl 0.3 M, NaH2PO4
GPC (manufactured by Showa Denko KK); column ShodexOHpakSB-G / ShodexOHpakSB
-806 / ShodexOHpakSB-803HQ, RI detector) as a weight average molecular weight using a polysaccharide as a standard.

[0019]

[Example 1] 11.0 g of water-soluble starch (dry amount) in a 1 L four-necked flask equipped with a stirrer, a condenser, a thermometer, and a pH electrode
, 4.0 g and 600 ml of sodium phosphotungstate
Of water was added and suspended. 35% hydrogen peroxide solution
20.0 g was added, the mixture was heated to 80 ° C. while adjusting the pH to 3.0 with an aqueous sodium hydroxide solution, and stirring was continued for 10 hours.
Next, the reaction mixture was cooled, a part thereof was sampled and subjected to iodometric titration analysis. As a result, the conversion rate of hydrogen peroxide was 90%. The remaining solution was added to 2 volumes of ethanol with stirring, the supernatant was discarded, the remaining precipitate was redissolved in water, and ethanol was added. Repeat the precipitation operation, and then freeze-dry the remaining precipitate. A polycarboxylated starch was obtained. The obtained polycarboxylated starch was treated with an H-type cation exchange resin to give an acid form, and then titrated with an aqueous sodium hydroxide solution. As a result, the carboxyl group content was 1.2 meq / g. The weight average molecular weight measured by GPC was 12,000.

[0020]

Example 2 11.0 g (dry amount) of soluble starch was placed in a reaction vessel similar to that used in Example 1, and 4.0 g of sodium phosphotungstate and 600 ml of water were added and suspended. To this, add 20.0 g of 35% hydrogen peroxide aqueous solution and heat to 80 ° C while adjusting the pH to 3.0 with sodium hydroxide aqueous solution.
Stirring was continued for 10 hours. Next, this reaction mixture is mixed with SUS304.
The mixture was transferred to an autoclave manufactured by the company, oxygen was supplied from an oxygen cylinder, the pressure was increased to 9 kgf / cm2 · G, the temperature was raised to 100 ° C, and stirring was continued for 4 hours. When the reaction mixture was cooled, a part of it was sampled and subjected to iodometric titration analysis, the conversion rate of hydrogen peroxide was 100%.
Met. The remaining liquid was treated and analyzed in the same manner as in Example 1, and as a result, the carboxyl group content was 1.5 meq / g. The weight average molecular weight measured by GPC is 3,
It was 000.

[0021]

Example 3 11.0 g (dry amount) of corn starch was placed in the same reaction vessel as used in Example 1, and 3.5 g of sodium phosphomolybdate and 600 ml of water were added and suspended. To this was added 20.0 g of 35% hydrogen peroxide aqueous solution, the mixture was heated to 90 ° C. while adjusting the pH to 3.5 with an aqueous sodium hydroxide solution, and stirring was continued for 12 hours. The reaction mixture is then SU
It was transferred to an autoclave made of S304, oxygen was supplied from an oxygen cylinder, pressurized to 5 kgf / cm 2 · G, heated to 110 ° C, and continued stirring for 3 hours. The reaction mixture was cooled, and a part thereof was sampled and subjected to iodometric titration analysis.
0%. The remaining liquid was treated in the same manner as in Example 1 and analyzed, and as a result, the carboxyl group content was 1.3 meq / g.
Met. The weight average molecular weight measured by GPC is
It was 5,000.

[0022]

Comparative Example 1 11.0 g (dry amount) of water-soluble starch was taken, and 4.0 g of sodium phosphotungstate and 600 ml of water were added and suspended. SUS304 without adding hydrogen peroxide solution
The mixture was placed in an autoclave manufactured by the company, oxygen was supplied from an oxygen cylinder, the pressure was increased to 9 kgf / cm 2 · G, the temperature was raised to 100 ° C, and stirring was continued for 4 hours. Thereafter, the same treatment as in Example 1 was carried out and the result of the analysis was that the carboxyl group content was 0.1 meq / g.

[0023]

EFFECTS OF THE INVENTION According to the method of the present invention, a polycarboxylic acid type polysaccharide having a high carboxyl group content can be efficiently obtained from a polysaccharide, and a halogenated salt which is a defect of the conventional method is not produced as a by-product. Therefore, it is suitable as an industrial method for producing a polycarboxylic acid type polysaccharide.

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Claims (2)

[Claims] 1. A method for producing a polycarboxylic acid type polysaccharide, which comprises contacting a polysaccharide and hydrogen peroxide in the presence of a heteropolyacid as a catalyst to carry out an oxidation reaction. 2. A method for producing a polycarboxylic acid-type polysaccharide, which comprises contacting a polysaccharide with hydrogen peroxide in the presence of a heteropolyacid as a catalyst, and then oxidizing the same with oxygen.