Imidazolium Based Ionic Liquids as Solvents for Cellulose Chemistry

In recent years, ionic liquids developed to advantageous solvents for the dissolution and homogeneous processing of cellulose. Even if ionic liquids were already known for their capability of efficiently dissolving cellulose for a long time, significant efforts were made in the last years. New candidates were found, but it could be shown, that some ionic liquids are involved in side reactions, too. With the aim for gaining a better insight on the dissolution properties, we screened a wide range of potentially suitable ionic liquids. Remarkable results were obtained, for example an odd-even effect was found for different alkyl side chain lengths, both linear and branched, for the imidazolium based ionic liquids with chloride counterions. Furthermore, 1-ethyl-3-methylimidazolium diethyl phosphate showed promising properties for the dissolution of cellulose, e.g. a lower degradation of cellulose than for other ILs, a low melting point, and a low viscosity of the cellulose solution, simplifying the handling.