JPS6119641B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing chitin derivatives by esterifying chitin. Chitin is found in shellfish such as shrimp and crabs, butterflies,
It is a polysaccharide consisting of poly-N-acetyl-D-glucosamine polycondensed with β (1→4) bonds, which is found in insects such as beetles and is widely distributed in nature. Since chitin has a chemical structure similar to cellulose, attempts have been made for a long time to use it in fibers and thin films, which are the main uses of cellulose.Recently, chitin has been used in semipermeable membranes and food packaging materials as an alternative to biological membranes. Applications are being considered. However, unlike cellulose, chitin has a crystal structure due to extremely strong intermolecular forces with aminoacetyl groups in its molecules, and it is hardly soluble in general inorganic or organic solvents, so it is only used in the form of xanthogens. However, its development is delayed. Attempts have been made to research fibers and thin films made from chitin alone, but they tend to be brittle, and as an improvement, chitin is immersed in a concentrated sodium hydroxide aqueous solution, the resulting alkali chitin is frozen at a low temperature, and then xanthogens are extracted with carbon disulfide. There has only been a report on a method for producing chitin and cellulose mixed fibers by mixing chitin viscose obtained by oxidizing and dissolving in an aqueous sodium hydroxide solution with cellulose viscose. The present inventors have investigated various methods for efficiently shaping chitin into fibers and thin films by slightly modifying the structure of chitin without impairing its properties, giving it even better properties. The present invention was achieved by discovering that if chitin is acetylated in the presence of a special solvent, a chitin derivative that can achieve the desired purpose can be obtained. That is, the gist of the present invention is to prepare chitin with the general formula in the presence of methanesulfonic acid or perchloric acid.

[Formula] (R, R' are CnH _2o+1 , n is an integer of 1 or more) to perform esterification. Preferably, the compound represented by the general formula here includes acetic anhydride and propionic anhydride, but is not limited thereto. Most preferably acetic anhydride is used. For example, chitin derivatives that have been acetylated with acetic anhydride rapidly increase in solubility in formic acid and become diacetyl chitin.85
It is also easily soluble in % formic acid. As acetylation progresses, a fiber thin film obtained from an acetyl derivative of chitin has an increased refractive strength and a supple texture compared to a fiber or thin film made of chitin alone. In the case of acetyl chitin, the specific esterification method of the present invention involves adding chitin to a mixture of methanesulfonic acid and acetic anhydride or glacial acetic acid and acetic anhydride at 0°C.
An arbitrary acetylated product can be obtained by treating the mixture overnight with acetic acid, or by treating with acetic anhydride containing 0.5 to 40 wt% perchloric acid at 0°C for several hours. Other esterified products can also be produced by appropriately changing the compound shown in the general formula. The esterified product thus obtained is poured into water, precipitated, washed with water, separated, dissolved in an arbitrary solvent such as formic acid, dichloroacetic acid or methanesulfonic acid, and then shaped into a desired form. The solution is extruded through a nozzle or T-die at a temperature higher than the melting point of the solution, preferably 10°C higher than the melting point. The present invention will be specifically explained below using Examples.
Chitin was obtained by treating red king crab with dilute hydrochloric acid and then treating it with hot dilute alkali to separate the protein.The chemical formula is C ₈ H ₁₁ NO ₃ (OH) ₂ 1/2 H ₂ O (analytical value C: 44.96).
%, H: 6.50%, N: 6.57%) The indicated powders were used. Parts represent parts by weight. Example 1 A calculated amount of acetic anhydride required for acetylation was added to a mixture of 4 parts of methanesulfonic acid and 6 parts of glacial acetic acid cooled to 0°C. To this was added 1 part of chitin with stirring, and after standing at 0° C. overnight, ice water was added to the reaction mixture to precipitate it. After washing with water, it was neutralized with distilled water and aqueous ammonia and boiled for 1 hour. The precipitate was separated and dried. Acetyl chitin with various degrees of acetylation was obtained by this method. Table 1 shows the amount of acetic anhydride, the degree of acetylation, and the elemental analysis values.

【table】

[Table] Example 2 6 parts of acetic anhydride and 4 parts of methanesulfonic acid were mixed at 0°C, and 1 part of chitin was added with stirring. Approximately 5
It became viscous over time. After standing overnight at 0° C., ice water was added to the mixture to precipitate it, and the resulting precipitate was washed in the same manner as in Example 1. The obtained acetylated product is thought to have the following chemical formula from elemental analysis. It was easily soluble in 99% formic acid and 85% formic acid. [C ₈ H ₁₁ NO ₃ (OCOCH ₃ ) ₂ ] Analytical values C: 49.46%, H: 6.00%, N: 4.72% Calculated values C: 50.17%, H: 5.92%, N: 4.88% Example 3 Water in a 60% aqueous perchloric acid solution and equimolar acetic anhydride were added and allowed to stand at 0°C overnight to prepare a perchloric acid-glacial acetic acid solution. 10 parts of acetic anhydride was mixed with 2 parts of this solution, and after cooling to 0°C, 1 part of chitin was added with stirring, and the mixture was reacted at 0°C for 3 hours. The resulting gravy-like reaction product was poured into a large amount of ice water to precipitate it and was treated in the same manner as in Example 1 to obtain a precipitate. The obtained acetyl compound is thought to have the following chemical formula from elemental analysis. [C ₈ H ₁₁ NO ₃ (OCOCH ₃ ) ₂ ] Analysis value C: 50.00%, H: 6.14%, N: 4.76% Calculated value C: 50.17%, H: 5.92%, N: 4.88% Example 4 Example Acetyl chitin 10 corresponding to No. 2 of 1
1 part was dissolved in 180 parts of 99% formic acid, and 20 parts of dichloroacetic acid was added to make a dope of about 100 poise. This is extruded through a platinum nozzle (0.5 mm x 40 H), sent to a mixture of isopropyl ether in the first coagulation bath, 5 ethanol in the second coagulation bath, 1 part acetic acid, and 1 part water, stretched in a water bath at a stretching ratio of 1.32 times, and wound up. Ivy. The obtained thread was transparent and had a supple feel. Example 5 99% of 10 parts of acetyl chitin obtained in Example 3
The mixture was dissolved in 40 parts of formic acid, 20 parts of ethylene chloride was added, the mixture was uniformly dispersed, and the mixture was filtered through a flannel cloth. This was treated in the same manner as in Example 4, stretched at a stretching ratio of 1.45 times, wound up, and washed with boiling water and dried. The obtained thread was transparent and had a supple feel. Example 6 1 part of chitin was added to 6 parts of propionic anhydride containing 4 parts of methanesulfonic acid at 0° C. with stirring.
The viscous liquid was left at 0° C. for 10 hours, precipitated in ice water, and washed in the same manner as in Example 1. The obtained propionylated compound was thought to have the following chemical formula from elemental analysis. [C ₈ H ₁₁ NO ₃ (OCOC ₂ H ₅ ) ₂ ] Analytical value C: 52.95%, H: 6.71%, N: 4.38% Calculated value C: 53.33%, H: 6.67%, N: 4.44%

Claims (1)

[Claims] 1. Chitin is treated with a compound of the general formula [Formula] (R and R' are CnH _2o+1 and n is an integer of 1 or more) in the presence of methanesulfonic acid or perchloric acid. A method for producing a chitin derivative, which comprises esterifying the chitin derivative.