Preparation of Cellulose Succinates with High Degree of Substitution in Solvent System [C4mim]Cl/DMSO

Abstract

Homogeneous derivatization of cellulose was investigated with succinic anhydride (SA) in a solvent system containing 1-butyl-3-methylimidazolium chloride ionic liquid ([C4mim]Cl) and dimethylsulfoxide (DMSO) using iodine, N-bromosuccinimide (NBS), and 4-dimethylaminopyridine (DMAP) as a catalyst. The results showed that the high degree of substitution (DS) of modified cellulose significantly increased from 0.24 without any catalysts to 0.84, 2.31, and 2.34 under same conditions except with I2, NBS, and DMAP, respectively, as a catalyst. The possible mechanism of succinoylation catalysed with different catalysts was discussed. Fourier transform infrared and solid-state cross-polarization/magic angle spinning 13C NMR spectroscopies also provided evidences of catalyzed homogeneous succinoylation reaction. The results indicated that iodine, NBS, and DMAP could effectively improve the succinoylation efficiency of cellulose in [C4mim]Cl/DMSO.