Chlorination of chitin with sulfuryl chloride under homogeneous conditions

Chitin was chlorinated with sulfuryl chloride under homogeneous conditions in LiCl-N,N-dimethylacetamide. Chlorodeoxychitins were obtained in the reactions at temperatures from -30 to 70 degrees C. The regioselective replacement of C-6 hydroxyl groups with chlorine atoms occurred in the reaction for 4 h at -20 degrees C while C-3 hydroxyl groups were also replaced above 0 degrees C when the molar ratio of sulfuryl chloride to the repeating unit of chitin was 15. The yield of chlorodeoxychitin decreased from 90 to 60% with the rise in reaction temperature from -30 to 60 degrees C and dropped to 27% at 70 degrees C. All the chlorodeoxychitin samples were soluble in formic acid. (C) 1997 Elsevier Science Ltd.