Gg. Allan et M. Peyron, MOLECULAR-WEIGHT MANIPULATION OF CHITOSAN .1. KINETICS OF DEPOLYMERIZATION BY NITROUS-ACID, Carbohydrate research, 277(2), 1995, pp. 257-272
The kinetics of the depolymerization of chitosan in dilute aqueous HCl
solutions by nitrous acid were studied. The rate of depolymerization
is independent of the molecular weight of chitosan, first order with r
espect to the concentrations of both nitrous acid and glucosamine moie
ties, not catalysed by either hydrogen or chloride ions, and Arrhenius
temperature dependent. Chitosan exhibits significantly decreased reac
tivity as the degree of deacetylation of the polymer increases. These
results are consistent with a depolymerization reaction mechanism in w
hich the rate-limiting step is nitrosation of the unprotonated amine b
y nitrous acidium ion.