Quaternary ammonium salt-functionalized chitosan: An easily recyclable catalyst for efficient synthesis of cyclic carbonates from epoxides and carbon dioxide

A quaternary ammonium salt covalently bound to chitosan is reported as an efficient and recyclable single-component catalyst for the synthesis of propylene carbonate (PC) from propylene oxide (PO) and carbon dioxide without any organic solvent or co-catalyst. The catalyst can be easily recovered by filtration and reused for at least five times without obvious loss of its catalytic activity. The effects of the catalyst structure and various reaction parameters on the catalytic performance were in detail investigated. Moreover, the catalyst was found to be applicable to a variety of terminal epoxides, producing the corresponding cyclic carbonates in high yield and selectivity. Notably, this environmentally benign and cost-effective process has great potential to be applied in various continuous flow reactors in industry. (C) 2007 Elsevier B.V. All rights reserved.