Synthesis and reduction of azidodeoxy derivatives of chitin

Azidodeoxychitin samples were obtained in the reactions of bromodeoxychitin and chlorodeoxychitin samples with sodium azide in polar aprotic solvents. A kinetic equation for a bimolecular reversible reaction was applicable to the azidation of 6-bromo-6-deoxychitin. The rate constant for the exchange with azide ion and the equilibrium constant were 7.36X 10-'M-1 min-' and 57.0 at 50•Ž, respectively, in the binary solvent system of lithium bromide and N,N-dimethylacetamide while they were 88.5 X 10-3 M-'min-' and 0.37, respectively, for the reaction at 60•Ž in methyl sulfoxide. The exchange with azide ion was
slower in the case of 6-chloro-6-deoxychitin samples. Azidodeoxychitin samples were reduced with sodium borohydride in methyl sulfoxide for 24 h at 60'C. Azido groups were consumed almost completely and the selectivity for the reduction to amino groups was higher than 80%.