Preparation of sugarcane bagasse cellulosic phthalate using an ionic liquid as reaction medium

Abstract

The chemical modification of sugarcane bagasse cellulose with phthalic anhydride using 1-butyl-3-methylinidazolium chloride ionic liquid as reaction medium was studied. A series of phthalated cellulosic derivatives were prepared with a degree of substitution (DS) ranging from 0.12 to 2.54. It was found that the DS increased with reaction temperature from 85 to 100 °C, molar ratio of phthalic anhydride/anhydroglucose units in cellulose from 2:1 to 10:1, and reaction time from 20 to 120 min. The products were characterized by FT-IR and solid-state CP/MAS 13C-NMR spectroscopy, and thermal analysis. The results showed that modification of cellulose with phthalic anhydride using 1-butyl-3-methylimidazolium chloride ([C 4mim]Cl) as solvent resulted in the production of cellulosic monoester, and the phthalation at C-6, C-2, and C-3 positions of the cellulose all occurred. In addition, it was found that the crystallinity of the cellulose was completely disrupted and the native cellulosic polymer was significantly degraded in the ionic liquid system under the conditions given. The thermal stability of the phthalated cellulose decreased upon chemical modification.