Chemical modifications of lignin for the preparation of macromers containing cyclic carbonates

Abstract

An epoxidized lignin derivative was prepared directly inserting epichlorohydrin on the phenolic functionalities. The epoxidized lignin was then converted to cyclic carbonates through the coupling reaction of CO₂ with the oxirane rings. Imidazolium based ionic liquids, acting as both solvents and catalysts, were successfully employed in the carbonation reaction. Moreover, the ionic liquid was reused up to three times without significant loss in activity. Finally, an exhaustive spectroscopic characterization was carried out on the epoxidized and carbonated lignins by quantitative ³¹P and ¹³C NMR analyses.