Ionic liquids and their application in cellulose chemistry

Ionic liqs. were recently found to dissolve cellulose, the most abundant biorenewable polymer in nature with a broad range of applications. Ionic liqs. are considered to be -green' solvents in comparison to conventional cellulose solvents, like carbon disulfide or N-methylmorpholine-N-oxide, due to their interesting properties like non-volatility, non-flammability and their recycability. In the present work 1 alkyl-3-methyl-imidazolium based ionic liqs. contg. chloride as a counter ion were used to dissolve cellulose. The influence of different alkyl chain lengths on the dissoln. of cellulose was investigated. The alkyl chain length was varied from Et to decyl, including both even and odd numbered chains, to elucidate structure-dissoln. properties revealing a remarkable odd-even effect. The tritylation of cellulose was performed in 1-butyl-3-methyl-imidazolium chloride using pyridine as base (see Figure). The influence of the reaction time and the ratio of trityl chloride per cellulose monomer unit on the degree of substitution were investigated in detail.