Studies On The Deacetylacing Reaction Of Chitin And The Preparation Of Its Ramification

Chitin is one of a natural macromolecule organic compound. It is very important to study the reactions of chitin deacetylacing and preparation of chitin ramification. Based on the research before, four kinds of studies were made in this paper: a, study on the optimum reaction condition of chitin deacetylacing; b, study on the analysis of carboxymethyl-chitosan made by different ways; c, study on the comparison between two kinds of preparation procedure of dissoluble chitin; d, study on the making of crystallite. The results are as follow:It was proved that three facts, alkali concentration, time and temperature, were very important in chitin deacetylace reaction. The degree of chitin deacetylation, the marker of the chitin deacetylacing reaction, increased with the increasing of the three facts. Among the facts, alkali concentration was the most important fact. And the time and temperature were also contributed much to the reaction, hi the reaction, the changing of viscosity was used to estimate the course of reaction and the contribution of the facts. During the early period of the reaction, the chitin deacetylation and the viscosity increased with the increasing of alkali concentration. After the viscosity arrived at the peak, the degree of chitin deacetylation increased slowly and viscosity did not increased but decreased The same effect of temperature on the changing of the degree of chitin deacetylation and viscosity was found in this paper. The effect of time on them was progressive. Further study showed that during the early reaction, the increasing of the chitin deacetylacing degree was due to the end-hydrolyzed reaction with alkali medium. But during the latter period of the reaction, the indican bonds were destroyed by alkali under higher temperature, and as a result, viscosity decreased in the long run.Compared the chitosan carboxymethylation reaction condition, it was found that the degree of chitosan carboxymethylation increased with a suitable advance activating procedure. Alkali was very powerful activating material. The first step of replacing reaction was that O was replaced by carboxymethyl. And further replacing reaction was that O and N were replaced by carboxymethyl. Freezing was also helpful to activate the chitosan and the main replacing reaction was o-replaced reaction.Acylated by acyl chloride, about 50% of the degree of deacetylation soluble chitosan were obtained from chitosan with more than 90% degree of deacetylation if the reaction conditions were controlled properlyCrystallite chitin was made in two different ways in this paper and chitin crystal was also obtained.Chitosan, carboxymethyl-chitosan, soluble chitosan, and crystallite chitin were qualitatively analysized by intrared spectrum to identify their structures.