Molecular weight manipulation of chitosan. I: Kinetics of depolymerization by nitrous acid.
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 respect to the concentrations of both nitrous acid and glucosamine moieties, not catalysed by either hydrogen or chloride ions, and Arrhenius temperature dependent. Chitosan exhibits significantly decreased reactivity as the degree of deacetylation of the polymer increases. These results are consistent with a depolymerization reaction mechanism in which the rate-limiting step is nitrosation of the unprotonated amine by nitrous acidium ion.
Allan
G G
GG
Department of Chemical Engineering, University of Washington, Seattle 98195, USA.
Peyron
M
M
D002240:Carbohydrate Sequence; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D048271:Chitosan; D002712:Chlorides / Q000737:chemistry; D006851:Hydrochloric Acid / Q000737:chemistry; D006868:Hydrolysis; D007700:Kinetics; D008969:Molecular Sequence Data; D009608:Nitrous Acid / Q000737:chemistry*; D011522:Protons; D013696:Temperature
D002712:Chlorides; D011522:Protons; D002686:Chitin; D048271:Chitosan; D006851:Hydrochloric Acid; D009608:Nitrous Acid