Tosylation of N-Phthaloyl-Chitosan without Drying of Solvents and Purging of Water Vapor
Keywords:tosyl, tosylation, phthaloyl, phthaloylation, chitosan
Tosylation of N-phthaloyl-chitosan, without pretreatment of solvent drying and without treatment of water vapor purging during the reaction has been studied. N-phthaloyl-chitosan was tosylated using excess tosyl chloride in dimethyl acetamide/LiCl as solvent and triethyl amine as catalyst at temperature < 10°C for 12 h. As comparison, the tosylation reaction was also performed using phthaloyl-chitosan (protection of chitosan by phthaloyl group was not chemoselective at amine groups only) as a raw material. The solvents were not dried prior to use and all subsequence reactions were not performed under nitrogen atmosphere. The result showed that by using phthaloyl-chitosan as a raw material, there is no product of tosylation can be isolated. The FTIR spectrum showed that 6-O-tosyl-N-phthaloyl-chitosan could be formed using CPNPC as raw material. It indicated that the success of tosylation can be influenced by selectivity of phthaloyl group protection on chitosan. These results showed that a tosylated- chitosan can also be prepared without pretreatment of solvent drying and treatment of water vapor purging during the reaction.