Fragmentation of Chitosan by Acids

Abstract

Fragmentation of chitosan in aqueous solution by hydrochloric acid was investigated. The kinetics of fragmentation, the number of chain scissions, and polydispersity of the fragments were followed by viscometry and size exclusion chromatography. The chemical structure and the degree of N-acetylation (DA) of the original chitosan and its fragments were examined by 1H NMR spectroscopy and elemental analysis. The kinetic data indicates that the reaction was of first order. The results of polydispersity and the DA suggest that the selected experimental conditions (temperature and concentration of acid) were appropriate to obtain the fragments having the polydispersity and the DA similar to or slightly different from those of the original one. A procedure to estimate molecular weight of fragments as well as the number of chain scissions of the fragments under the experimental conditions was also proposed.

Structural Characterization of Oligochitosan Elicitor from Fusarium sambucinum and Its Elicitation of Defensive Responses in Zanthoxylum bungeanum

“…Oligochitosan was prepared by degradation of chitosan using hydrochloric acid according to a previously reported method with some modifications [75]. Deacetylated chitosan (8 g) was added to 1.2% acetic acid solution and stirred until the mixture was gelatinous.…”

Modification of Chitosan for the Generation of Functional Derivatives

“…Depolymerization of CS is principally performed by acid chitosanolysis, which is the most reported method for producing COS and LMW CSs [4]. Overall, chemical processes include chitosanolysis with HCl [56], HNO 2 [57], H 2 O 2 [58], and potassium persulfate [59].…”

Catalisadores ácidos baseados na simples modificação da quitosana para a esterificação do ácido oleico

“…Já para o material Q2, foi observada a presença de quatro eventos térmicos: o primeiro evento que ocorre na faixa de temperatura de 26-165°C correspondendo a uma perda de massa de 19,5 % está relacionada,principalmente, à perda de água adsorvida na superfície do material; o segundo evento (perda de massa de 39,5 % entre 165-211°C) e o terceiro evento ( perda de massa de 24,3 % e faixa de temperatura de 211-337°C), estão associados à liberação de compostos orgânicos, e o quarto evento de perda de massa foi de aproximadamente 16,7% entre as temperaturas de 337-800°C, correspondendo à perda dos grupos sulfatos e carbonização do material [41,42].…”

“…A análise do material Q2 evidenciou uma maior estabilidade térmica na mesma faixa de temperatura que o material Q1 (entre 160-300° C). Isso pode ser explicado pelas fortes interações covalentes existentes resultantes do processo de reticulação promovida pelos grupos sulfato [32,[42][43][44].…”