Homogeneous acylation of eucalyptus wood at room temperature in dimethyl sulfoxide/N-methylimidazole

Abstract

Succinoylation and benzoylation of ball-milled eucalyptus wood using succinic anhydride and benzoyl chloride as acylating reagent, respectively, were investigated at room temperature using dimethyl sulfoxide/N-methylimidazole (DMSO/NMI) as reaction medium without additional catalysts. The effects of the corresponding acylating reagent dosage (1–5:1 for succinoylation and 0.5–5:1 for benzoylation) and reaction time (0.35–5h for succinoylation and 0.5–3h for benzoylation) on the extent of acylation, measured by weight percent gain (WPG), were studied. WPG of succinoylation and benzoylation was in the range of 70.8–144.7% and 17.3–43.1%, respectively. The efficiency of acylation at room temperature significantly increased in DMSO/NMI compared with ionic liquid 1-butyl-3-methylimidazolium chloride because of the role of NMI as solvent, base and catalyst. Fourier transform infrared (FT-IR), and solid-state cross-polarization/magic-angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) spectroscopy studies provided evidence for the occurrence of succinoylation and benzoylation reactions and the attachment of functional groups via ester bonds.