Unexpected chloro-functionalized ionic liquids-promoted selective conversion of cellulose into levulinic acid

A series of chloro-functionalized ionic liquids (CFILs) with chlorine groups (–Cl) on cations and chloride anions (Cl-) were synthesized and used as the promotion reagents for the selective conversion of cellulose into levulinic acid (LA) with the co-product of formic acid (FA). The co-operation between cations and anions of CFILs was investigated intensively through the variation of the structure of cations and the addition of salts with different anions. 3-(3-chloropropyl)-1-methyl-imidazolium chloride (IL-3) was the most appropriate additive, achieving up to 4.2%, 52.6%, and 58.7% of glucose, LA, and FA yields at 83.5% of cellulose conversion, respectively.