Imidazolium Chloride-LiCl Melts as Efficient Solvents for Cellulose

Abstract

1-Alkyl-3-methylimidazolium chloride-LiCl melts were prepared from the reaction of 1-alkyl-3-methylimidazolium chloride ([RMIm]Cl; R=allyl or n-butyl) and lithium chloride, and their ability to dissolve cellulose was evaluated. The solubility of cellulose was greatly increased to 320% when [RMIm]Cl was replaced by [RMIm][LiCl2]. Dissolved cellulose in LiCl/[RMIm]Cl melts was successfully regenerated by adding water and LiCl/[RMIm]Cl melts were easily recovered by removing water. As supported by the computational results, the higher solubility of cellulose in [RMIm][LiCl2] can be ascribed to the increased bond distance between anion and C(2)-H of the imidazolium ring compared with that in [RMIm]Cl, thereby resulting in the increased interaction between [LiCl2](-) and the hydroxyl groups of cellulose..