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Microwave process for preparing carboxymethyl chitosan

A technology for carboxymethyl chitosan and chitosan, which is applied in the field of preparing carboxymethyl chitosan by improving carboxylation reaction conditions, can solve the problems of high cost and long reaction time, and achieves short reaction time and easy operation. , the effect of low cost

Inactive Publication Date: 2002-08-14
徐云龙
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved in the present invention is to disclose a new method for preparing carboxymethyl chitosan, which comprises taking chitosan as a raw material, first carrying out swelling alkalization of chitosan, and then carrying out radiation carboxylation with microwaves, Obtain carboxymethyl chitosan to overcome the defects of long reaction time and high cost in the prior art

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Weigh 3g of chitosan, prepare 18g of sodium hydroxide to a 45% concentration solution, measure 45mL of ethanol solution, add them into a microwave reactor in turn, and alkalize at 30°C for 1h. Weigh 27g of chloroacetic acid, slowly add it into the reactor under stirring, and react for 25min. Separate the ethanol solution in the upper layer with a separatory funnel. Then add 100ml of distilled water to dissolve, and adjust the pH value to about 7.0 with dilute hydrochloric acid, filter out the insoluble matter, add 4 times the amount of ethanol to the filtrate to precipitate, let stand, filter, then wash with 80% ethanol solution, and the precipitate is re-dissolved. After washing with acetone, suction filtration and vacuum drying, a 5.805 g sample was obtained. After testing, the degree of substitution of the sample was 0.98, the viscosity was 30 mPa.s, and the yield was 95%.

Embodiment 2

[0027] Weigh 3g of chitosan, prepare 21g of sodium hydroxide to a 50% concentration solution, measure 45mL of isopropanol solution, add them into a microwave reactor in turn, and alkalize at 30°C for 1h. Weigh 24g of chloroacetic acid, slowly add it into the reactor under stirring, and react for 30min. Separate the upper layer of the isopropanol solution with a separatory funnel. Then add 100ml of distilled water to dissolve, and use dilute hydrochloric acid to adjust the pH value to about 7.0, filter out the insoluble matter, add 4 times the amount of methanol to the filtrate to precipitate, let stand, filter, and then wash with 70% methanol solution, and the precipitate is re-dissolved. After washing with acetone, suction filtration and vacuum drying, a 5.379 g sample was obtained. After testing, the degree of substitution of the sample was 0.92, the viscosity was 28 mPa.s, and the yield was 90%.

Embodiment 3

[0029] Weigh 3 g of the sample in Example 2, prepare a 50% concentration solution with 21 g of sodium hydroxide, measure 45 mL of isopropanol solution, add them into a microwave reactor in sequence, and alkalize at 30° C. for 1 h. Weigh 24g of chloroacetic acid, slowly add it into the reactor under stirring, and react for 30min. Separate the upper layer of the isopropanol solution with a separatory funnel. Then add 100ml of distilled water to dissolve, and use dilute hydrochloric acid to adjust the pH value to about 7.0, filter out the insoluble matter, add 4 times the amount of methanol to the filtrate to precipitate, let stand, filter, and then wash with 70% methanol solution, and the precipitate is re-dissolved. After washing with acetone, suction filtration and vacuum drying, 3.05 g was obtained. After testing, the degree of substitution of the sample was 1.45, the viscosity was 20 mPa.s, and the yield was 61%.

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Abstract

A microwave process for preparing carboxymethyl chitosan includes such steps as wet expansion of chitosan, alkalization, carboxylating reaction by radiating it with microwave (300 MHz-6.4 GHz and 100W-10KW) for 2-60 min, separation and purification. Its advantages are short reaction time and low cost.

Description

technical field [0001] The invention relates to a method for preparing carboxymethyl chitosan by improving carboxylation reaction conditions. Background technique [0002] Carboxymethyl chitosan is obtained by chemically modifying chitosan under alkaline conditions with chloroacetic acid or glyoxylic acid as a modifier, and has good water solubility. Due to the special physical and chemical properties, chemical properties and physiological activities of carboxymethyl chitosan, it is widely used in agriculture, food, chemical industry, medicine and other fields, and has excellent properties that cannot be replaced by other derivatives. [0003] The carboxylation reaction process is a key step in the preparation of carboxymethyl chitosan technology, the current preparation technology such as "Study on the synthesis conditions of carboxymethyl chitosan" (Lin Youwen et al., Chemical World, 2000, 41 (8).-415 -417, 425), the alkalized chitosan was reacted with chloroacetic acid a...

Claims

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Application Information

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IPC IPC(8): C08B37/08
Inventor 徐云龙徐南苗储文英汪传木雷晓明刘惠兴
Owner 徐云龙
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