Ring-opening copolymerization of epoxides and anhydrides using manganese(iii) asymmetrical Schiff base complexes as catalysts

Abstract

Based on a series of asymmetrical Schiff base H₂Lⁿ (n = 1–4) ligands with different electronic and steric effects, a series of [Mn(Lⁿ)Cl] complexes 1–4 are obtained and shown to be effective catalysts in cyclohexene oxide and maleic anhydride, cyclohexene oxide and phthalic anhydride, styrene oxide and maleic anhydride or styrene oxide and phthalic anhydride ring-opening copolymerizations. Through the structure design, the input of the electron-withdrawing Br substituent para to the phenoxide group of the complexes is quite beneficial to the improved activities. Moreover, both steric and electronic effects of a suitable MeO substituent at the ortho position of the phenoxide group have much more influence on the formation of alternating ring-opening copolymers than that of selected reaction conditions.