Transition-metal-free/boric acid catalysed mechanochemical synthesis of symmetrical and unsymmetrical azobenzenes: a sustainable approach

Abstract

A mechanochemical protocol employing boric acid, an economical and environmentally benign inorganic acid catalyst, enables the synthesis of symmetrical and unsymmetrical azobenzenes from diverse amines. This grinding-based, solvent-free approach provides a sustainable alternative to conventional methods, avoiding harsh transition-metal catalysts. The use of oxone as a green oxidant, operation under ambient conditions, simplified work-up, and overall environmental compatibility highlight the advantages of this methodology.