Homogeneous tritylation of cellulose in 1-allyl-3-methylimidazolium chloride and subsequent acetylation: the influence of base.

Abstract Homogeneous tritylation of cellulose in 1-allyl-3-methylimidazolium chloride (AmimCl) ionic liquid with triphenylmethy chloride as regents, pyridine or 1-butylimidazole (BIM) as base was investigated, and subsequent acetylation of the 6- O -functionalized products was further studied. The structure of products was analyzed by FTIR and 13 C NMR spectroscopy and base influences on the structure were discussed as well. The solution with pyridine as base underwent heterogeneous–homogeneous–heterogeneous process and the obtained trityl cellulose (TC) had organized structure with trityl group located completely at C-6 position of cellulose with maximum DS trityl of nearly 1. In the case of BIM as base, the solution was homogeneous for the whole reaction, but the highest DS trityl was about 0.22, with trityl group located not only at position 6 but also partially at position 2. Subsequent acetylation of the TC led to products with a preferred functionalization of the unprotected secondary OH-groups.