JP2619304B2 - Method for producing hydroxypropylated deacetylated chitin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention does not require a special pressure vessel or catalyst, and uses only water as a reaction medium. It is a very simple and industrially useful method for producing hydroxypropylated deacetylated chitin having high industrial value. About.

[0002]

2. Description of the Related Art Hydroxypropylated polysaccharide is one of the important water-soluble derivatives of polysaccharide, and it is well known that hydroxypropylated cellulose is already widely used. Further, for example, hydroxypropylated deacetylated chitin, which is a kind of hydroxypropylated polysaccharide, is a water-soluble polymer useful for various uses such as a raw material for cosmetics, as described in JP-B-64-5601.
Conventionally, in producing this hydroxypropylated deacetylated chitin, a strong alkali catalyst such as sodium hydroxide is used as an essential component as described in the above publication, and hydroxypropylation is carried out under pressure and in an organic solvent system. I was

[0003]

However, needless to say, in order to carry out the reaction under pressure, a pressure vessel is required, and there is a problem that various restrictions and dangers are involved. In addition, the use of an organic solvent also poses problems such as danger to fire and remaining in products. There is also a problem that the use of a strong alkali catalyst requires a great deal of labor to remove it.

[0004] Also, hydroxypropylated deacetylated chitin is important as a base for measuring the activity of an enzyme. As a method for producing this, hydroxypropylation of deacetylated chitin is carried out under normal pressure and using water as a solvent. That is being done. However, also in this case, it is essential to use sodium hydroxide as a catalyst, which involves the same problem. Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a method for easily producing hydroxypropylated deacetylated chitin without using a catalyst under normal pressure and without using an organic solvent system. To provide.

[0005]

The above objects are achieved by the present invention described below. That is, the present invention is a method for producing hydroxypropylated deacetylated chitin, wherein dehydroxylated chitin is subjected to hydroxypropylation under normal pressure without water using water as a reaction medium.

[0006]

The present inventors have conducted intensive studies on a simple method for producing a hydroxypropylated polysaccharide. As a result, if deacetylated chitin is used as a starting material, water can be used as a reaction medium under normal pressure and a catalyst can be added. Thus, the present inventors have found that a water-soluble hydroxypropylated deacetylated chitin can be obtained easily, and the present invention has been completed.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The deacetylated chitin used in the present invention is a kind of natural polymer contained in crustaceans such as crabs, shrimps and insects, or mushrooms and the like.
Basic deacetylated chitins having 2-deoxy-D-glucose as one constitutional unit. Such deacetylated chitin itself has already been industrially produced and various grades are available on the market. Any of these known deacetylated chitins can be used in the present invention. For example, depending on the use of the final product produced by the method of the present invention, a relatively high-viscosity deacetylated chitin is used when producing a substance to be used as a thickener, while a coating agent is used. In the case of producing the same, deacetylated chitin having a relatively low degree of polymerization may be used as a starting material.

The degree of deacetylation is not particularly limited, but is preferably 50 to 50 in the present invention.
100%. Such hydroxypropylation of deacetylated chitin is performed in a dispersion system at the beginning of the reaction. The reaction medium at this time may be water alone, and the dispersion concentration is not particularly limited, but is preferably about 5 to 20 parts by weight per 100 parts by weight of the aqueous medium. The amount of propylene oxide used for the hydroxypropylation reaction is preferably about 100 to 800 parts by weight per 100 parts by weight of deacetylated chitin. Also, the reaction time at that time depends on the reaction temperature,
It is preferable that the reaction is carried out at a temperature of about the boiling point of the system by gradually raising the temperature during this period, for about 10 to 50 hours.

Next, the present invention will be described more specifically with reference to examples.

【Example】

Example 1 First, 9 g of deacetylated chitin having a degree of deacetylation of 82%
Was dispersed in 120 g of ion-exchanged water. Next, propylene oxide (4.5 g) was added thereto, and the mixture was heated to 85.5 ° C. over 1 hour and 30 minutes with stirring. After continuing the reaction for 3 hours in this state, when the liquid temperature reached 94.5 ° C., the mixture was once cooled to room temperature. After further adding 4.5 g of propylene oxide, the mixture was further reacted at the boiling point for 2 hours. After completion of the reaction, the mixture was allowed to cool, and the supernatant was decanted. Next, a large excess of isopropyl alcohol was added, and the mixture was stirred and filtered, and the filtrate was further washed with isopropyl alcohol. After drying at 50 ° C., 12 g of the desired hydroxypropylated deacetylated chitin was obtained. Although this product was insoluble in water as it was, it was dissolved by adding a small amount of acetic acid, and after that, even when neutralized with sodium hydroxide, it maintained a uniform aqueous solution state without precipitation.

Example 2 First, 9 g of deacetylated chitin having a degree of deacetylation of 70%
Was dispersed in 120 g of ion-exchanged water. Next, 9 g of propylene oxide was added thereto, and the mixture was heated to 65.0 ° C. over 1 hour and 30 minutes with stirring. After the reaction was continued for 5 hours in this state, when the liquid temperature reached 82 ° C., it was once cooled to room temperature. After further adding 9 g of propylene oxide, the reaction was further carried out at 56 ° C. for 4 hours. After completion of the reaction, the mixture was allowed to cool, and the supernatant was decanted. Next, a large excess of isopropyl alcohol was added, and the mixture was stirred and filtered, and the filtrate was further washed with isopropyl alcohol.
After drying at 50 ° C., 13 g of the desired hydroxypropylated deacetylated chitin was obtained. Although this was insoluble in water as it was, it was dissolved by adding a small amount of acetic acid, and after that, even when neutralized with sodium hydroxide, it remained in a uniform aqueous state without precipitation.

Example 3 First, 9 g of deacetylated chitin having a degree of deacetylation of 82%
Was dispersed in 120 g of ion-exchanged water. Next, 12 g of propylene oxide was added thereto, and the mixture was stirred for 1 hour and 30 hours.
Warmed to 57 ° C over minutes. In this state, the reaction was continued for 5 hours. When the liquid temperature reached 84 ° C., the mixture was once cooled to room temperature. After further adding 12 g of propylene oxide, the reaction was further carried out at the boiling point for 7 hours. After cooling, 13 g of propylene oxide was further added, and the reaction was further performed at the boiling point for 7 hours. During this time, the deacetylated chitin began to swell, and the viscosity of the reaction system increased significantly. Further, 11 g of propylene oxide was added and the reaction was carried out at the boiling point for 7 hours. As a result, most of the hydroxypropylated deacetylated chitin was dissolved in the reaction system. The reaction solution was filtered through a glass filter to remove a small amount of insoluble matter, thereby obtaining a target hydroxypropylated deacetylated chitin aqueous solution.

[0012]

As described above, according to the present invention, a pressure vessel,
It does not require organic solvents or strong alkali catalysts, has no danger of fire or residual solvent in the product, and does not require much effort for catalyst removal. The reaction can be carried out in the absence of a catalyst to easily produce hydroxypropylated deacetylated chitin.

Claims (1)

(57) [Claims] 1. A method for producing hydroxypropylated deacetylated chitin, wherein deacetylated chitin is subjected to hydroxypropylation using water as a reaction medium at atmospheric pressure without a catalyst.