The Effects of Acetate Anion On Cellulose Dissolution and Reaction In Imidazolium Ionic Liquids

Quantum mechanical calculations were carried out to determine the mechanisms for the superiority of the imidazolium acetate based ionic liquids for biomass processing to the corresponding chloride based ionic liquids. Our results indicate that imidazolium cation can react with the acetate anion to generate carbene, a highly reactive intermediate. Carbene produced then reacts with the reducing ends of cellulose to facilitate its dissolution in the ionic liquid solvents. The mechanisms for imidazolium cation and acetate anion reaction involve the initial ion pairing of the cation and anion via hydrogen bonding and electrostatic interactions. The hydrogen bond formed between the C2-H on the imidazolium cation and COO⁻ of the anion facilitates the transfer of the H⁺ to the anion to form a carbene intermediate.