Preparation of chitin-p-toluenesulfonate and deoxy(thiocyanato) chitin

Abstract Chitin- p -toluenesulfonate(tosyl-chitin) was prepared homogeneously in lithium chloride-N,N-dimethylacetamide (LiCl/DMAc). In this solvent system, the side reaction of O-acetylation often occurred by solvolysis of p -toluenesulfonyl(tosyl) chloride. The utilization of strong base either triethylamine or 4-dimethylaminopyridine, leads to highly tosylated chitin, with minimal incorporation of an O-acetyl group. Similar results were found in the substitution of N-methylpyrroridone (NMP) for DMAc. Chitin-4(methylamino)butylate was obtained with a pyridine catalyst. The degree of tosylation increased with increasing amount of tosyl chloride and became constant above 1. Tosyl-chitin obtained at high reaction temperature was highly chlorinated. The tosyl-chitin with high degree of substitution was readily soluble in various polar organic solvents such as dimethylsulfoxide (DMSO) and N,N-dimethylformamide (DMF). By X-ray analysis, it was observed that the crystallinity of tosyl-chitin became low as the reaction proceeded. Treating tosyl-chitin with potassium thiocyanate in DMSO produced deoxy(thiocyanato)chitin.