Heterogeneous Co-catalyzed dehydrogenative aromatization of cyclohex-2-enone and amines to 1,4-phenylenediamine

Abstract

A novel heterogeneous cobalt-silicotungstate polyoxometalate catalyst (CoSiW-300) for the aerobic dehydrogenative aromatization of cyclohex-2-enones and amines is described. This method efficiently construct both symmetric and unsymmetric 1,4-phenylenediamine derivatives in a single step from readily available precursors. Comprehensive characterization (XRD, FT-IR, XPS, Py-IR) confirmed the preservation of the Keggin-type structure and revealed the critical role of Lewis acid sites, whose strength and population are modulated by the calcination temperature. The CoSiW-300 catalyst demonstrated broad substrate scope, excellent functional group tolerance, and robust recyclability without significant loss of activity, underscoring its potential as a sustainable and economical alternative to noble-metal-based homogeneous systems.