Efficient epoxidation of olefins by immobilized (TEMPO)-co-(Chlorophyll b)/Co(III) polymer on magnetic NPs as a bi-functional, self-co-oxidant magnetically recyclable nanocatalyst: smart isolation with poly(benzoic acid)

Abstract

A selective and efficient olefin epoxidation has been developed by Fe₃O₄@SiO₂/(TEMPO)-copolymer-(Chlorophyll b)-Co^(III) NPs as a heterogeneous magnetically recyclable nanocatalyst. The nanocatalyst was synthesized through several steps including chlorophyll b de-metallation, imine functionalization with ally amine, co-polymerization with acrylated TEMPO, re-metalation with cobalt, and immobilization on magnetite NPs. Selective catalytic epoxidation of olefins was accomplished under mild conditions and in an O₂ atmosphere. High selectivity and conversion were achieved for a variety of substrates. The results indicated a synergistic effect between TEMPO moieties and the coordinated Co^(III) centers as two active sites. The epoxide products could be separated by the heterogeneous poly(benzoic acid) with the highest possible isolated yields. Also, the heterogeneous nanocatalyst could be recycled for at least 7 consecutive cycles with a negligible reactivity loss.

Graphical abstract

A selective and efficient olefin epoxidation with smart isolation has been developed by Fe₃O₄@SiO₂/(TEMPO)-copolymer-(Chlorophyll b)-Co^(III) NPs under mild conditions.