Ferrocene-based ionic liquids and related salts containing imidazolium/triazolium ring and their catalytic activity toward epoxy-anhydride ring opening copolymerization

Abstract

This study reports on the synthesis of four series of ferrocene-containing ionic liquids (Fc-ILs) and related salts with higher melting point (Fc-Ss) bearing an imidazolium and triazolium moiety on 0.3-g to 10-g scales. Representatives of each structure motif were scrutinized by cyclic voltammetry. In particular cases, X-ray crystallography on a single crystal was used to determine their molecular structures. This in-depth investigation revealed unreported side products formed during the particular syntheses. The full series of here reported Fc-ILs/Fc-Ss was tested for catalytic activity toward the ring-opening copolymerization of epoxy resin with cyclic anhydride. It revealed a significant role of the imidazolium/triazolium ring on the catalytic activity. Furthermore, the effect of immobilization of imidazolium-based Fc-S was investigated, revealing a significant increase in its catalytic activity, allowing a reduction in the amount of catalytically active Fc-S.