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

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 ¹³C 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.