JPS60206801A - Production of organic solvent-soluble alginic acid - Google Patents

Abstract

PURPOSE:To produce alginic acid soluble in some organic solvents, by replacing part or all of the H atoms of OH and carboxyl groups of alginic acid by hydrophobic groups. CONSTITUTION:An alginic acid gel prepared from Laminariaceae by a usual method is dehydrated and swollen by the addition of anhydrous acetone to obtain acetone-swollen alginic acid of an alginic acid content of about 5%. To this acetoneswollen alginic acid, about 12pts.vol., per pt.vol. alginic acid, formamide is added, and the mixture is violently agitated at room temperature, heated to about 50 deg.C and further agitated for about 1hr and cooled. After the addition of a trimethylsilylating agent (e.g., hexamethyldisilane), the resulting mixture is allowed to react for 30min at room temperature and agitated at 60 deg.C for about 2hr to replace part or all of the H atoms of OH and carboxyl groups by hydrophobic groups (e.g., trimethylsilyl groups.).

Description

Detailed Description of the Invention The present invention introduces a trimethylsilyl group, which is a hydrophobic group, into some or all of the hydroxyl group and carboxyl group, which are hydrophilic groups in alginic acid, thereby making it soluble in some organic solvents. The present invention relates to a method for producing alginic acid with specific properties.

Alginate Currently used for food, medicine, textile printing, paper manufacturing,
It is a natural high-grade polysaccharide that is widely used for welding rods and other purposes.It is acidic because it is different from the two types of phosphoric acid, D-mannuronic acid and L-guluronic acid, and is used as a polymer electrolyte. It has properties. In addition, since each uronic acid unit has five hydrophilic groups, it is water-soluble, and most of these uses are in the form of alginate, typified by lamb salt. It is marked @ for use only in water systems. In order to further expand the uses of alginic acid, the present inventors attempted to introduce a hydrophobic group into alginic acid to make it more soluble in organic solvents than K, and conducted research using a trimethylsilyl group as the hydrophobic group, resulting in the present invention. I ended up doing this.

That is, according to the present invention, a trimethylsilyl group, which is a hydrophobic group, is introduced into some or all of the hydroxyl groups and carboxyl groups of alginic acid, thereby making it resistant to lower glycol solvents such as ethylene glycol and propylene glycol, and formamide. It is possible to produce trimethylsilyl alginate derivatives that dissolve in water.

In the present invention, the alginic acid raw material used for introducing the trimethylsilyl group is prepared from alginic acid-containing brown algae by a known method. In other words, from a few hours to a day,
After swelling in water, it is exposed to dilute acid such as dilute sulfuric acid or dilute hydrochloric acid for usually 10 minutes to 3 hours, then homogenized with sodium carbonate for 1 hour to 10 hours, usually at a temperature of 30°C to 70°C, and then centrifuged. Alternatively, filtration is performed to obtain a clear extract containing 2 to 4 units of alginic acid. Sulfuric acid is added to this extract to gel the alginic acid contained therein, and a gel of dehydrated alginic acid is obtained by centrifugation or compression. Using this gel, a trimethylsilyl group is introduced into alginic acid by the method described below.

It is also difficult to use commercially available powdered alginic acid or an equivalent dry preparation as a raw material for introducing trimethylsilyl groups, but it has been pointed out that in this state, alginic acid may form intramolecular lactone bonds. and
Furthermore, it is possible that the reactivity with formamide used in the trimethylsilyl group introduction reaction may deteriorate due to a decrease in the dispersion state, so it is advantageous to use the gel produced by sulfuric acid, which is the method of the present invention, as a starting material.

The above starting material alginate gel is sufficiently dehydrated and swollen using anhydrous acetone. It is known that residual water in the gel greatly affects the efficiency of the trimethylsilylation reagent, so the gel is subjected to synthesis in a state in which water is removed as much as possible and at the same time it is sufficiently swollen in acetone. This acetone swelling treatment improves the dispersion state in the subsequent formamide, making it possible to further increase the trimethylsilylation rate.

Approximately 12 times the amount of formamide was added to the acetone-swollen alginic acid with an alginic acid content of approximately 5%, and the mixture was vigorously stirred at room temperature, heated to 50°C and further stirred for 1 hour, and after cooling, the trimethylsilylating agent was added and hexane was added. Add methyldisilazane and allow to react at room temperature for 60 minutes, then warm to 60° C. and stir for 2 hours.

Many trimethylsilylating agents are known in addition to hexamethyldisilazane, and although the use of other trimethylsilylating agents cannot be prevented, - for example, when using trimethylchlorosilazane, it is difficult to remove large quantities at a single point. However, it is possible that the dispersion of alginic acid in formamide is not adversely affected by the generation of hydrogen chloride due to the reaction.
Therefore, there are problems such as difficulty in separating secondary products by adding a solvent such as pyridine, so hexamethyldisilazane used in the present invention is advantageous.

Among the synthesis conditions, the important point regarding temperature conditions is that after adding hexamethyldisilazane, the mixture should be gradually stirred at room temperature for at least 30 minutes to allow hexamethyldisilazane to fully penetrate into the alginate gel. be. If hexamethyldisilazane is heated before it has fully penetrated into the alginate gel, the reaction will proceed only locally, and the remaining hexamethyldisilazane will only react with trace amounts of water in the system, resulting in hydrophobicity to alginic acid. Before imparting properties, the hydrophobicity of the slurry increases,
The reaction will end up being lumpy and the reaction will be insufficient. That is, it is important to maintain a sufficiently dispersed state of the alginate gel while the reaction proceeds.

The amount of hexamethyldisilazane added is the ratio of the number of moles of hydrogen that can be reacted in alginic acid to the number of moles of trimethylsilyl group in hexamethyldisilazane. The conversion rate is the highest, and a product is obtained in which about 50 moles of hydrogen that can be reacted in alginic acid are replaced with trimethylsilyl groups.

Addition of hexamethyldisilazane equivalent to 30 times or more the number of moles of trimethylsilyl groups is necessary because the reaction system is hydrophobic due to the hydrophobicity of hexamethyldisilazane. This results in a decrease in permeability and a decrease in the trimethylsilylation rate.

The present invention will be explained below with reference to Examples.

Example Brown algae raw material is swollen in a conventional manner, treated with acid or alkali to create an extract containing 2-4% alginic acid, and gelled and dehydrated by adding sulfuric acid to contain 75-85% water. Prepare alginate gel. This L is dehydrated by treating it with an excess amount of anhydrous acetone many times in a homogenizer to prepare an acetone-swollen alginic acid containing about 1 as alginic acid.

The acetone-swollen alginic acid 100fK hol.

Add 1100 m/~1200 m of amide, stir vigorously at room temperature for 1 hour, further stir at 50°C for 1 hour, and cool to room temperature. To this, add 336-
After dropping the mixture and reacting at room temperature for 30 minutes, the mixture was heated to 6°C and stirred for 2 hours. After cooling, the mixture is washed with a large amount of anhydrous Artone, dried and pulverized to produce a 1-methylsilyl alginate derivative.

[Brief explanation of drawings]

The figure shows the infrared absorption spectra of KBr tablets 1 of tri-alginate, tilsilyl-induced +11 and alginic acid (2) obtained according to the present invention. (No change in content) Biyu □ ν Default procedure amendment band (method) % formula % 1. Indication of case Patent Application No. 61065 of 1988 3.
Relationship with the case of the person making the amendment Patent applicant address (residence) 2-15 Uchikanda, Chiyoda-ku, Tokyo 101
Qiao No. 4 No agent

Claims (2)

[Claims] (1) A method for producing organic solvent-soluble alginic acid by introducing hydrophobic groups into some or all of the hydrogen atoms of the hydroxyl groups and carboxyl groups of alginic acid. (2) The method for producing an organic solvent-soluble trimethylsilyl alginate derivative according to claim 1, wherein the hydrophobic group is a trimethylsilyl group.