Preparation of a C sub(6) quaternary ammonium chitosan derivative through a chitosan schiff base with click chemistry

In this study, we explored a new method for preparing C sub(6) quaternary ammonium chitosan (CTS) derivatives. The C sub(2)--NH sub(2) of CTS was first protected by benzaldehyde. The C sub(6)--OH of CTS was then transformed into a sulfonyl ester, which was then reacted with NaN sub(3) through nucleophilic substitution to introduce the --N sub(3) group at the CTS C sub(6) position. This intermediate was reacted in a click chemistry reaction with a terminal alkynyl quaternary ammonium salt; this was followed by the deprotection of C sub(2)--NH sub(2) with acid to furnish the C sub(6) quaternary ammonium CTS derivative. The structures and properties of synthesized products in the reactions were characterized by Fourier transform infrared spectroscopy, NMR, X-ray diffraction, and thermogravimetric analysis, respectively. The effects of the reaction conditions on the degree of Schiff-base CTS quaternization were evaluated by elemental analysis. The largest inhibition zone test and the minimum inhibitory concentration test showed that compared with CTS, the prepared CTS derivative had significantly improved antibacterial activity toward Staphylococcus aureus and Escherichia coli. [copy 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013