Traditional and photocatalytic conversion of aniline into azocompounds – a comprehensive experimental and theoretical review

Abstract

The catalytic conversion of aniline into azo compounds represents a significant and versatile route in synthetic organic chemistry, with applications spanning dyes, pharmaceuticals, and functional materials. This comprehensive review systematically examines recent advances in catalytic strategies for azo bond formation from aniline derivatives, encompassing homogeneous, heterogeneous, enzymatic, and photo-redox catalysis. Key mechanistic pathways, including oxidative coupling, dehydrogenative aromatization, and redox processes, are critically analyzed. The influence of catalyst design (e.g., transition metals, organo-catalysts, nanomaterials) and reaction conditions (solvent, oxidants, temperature) on selectivity and efficiency is discussed. Additionally, the review highlights sustainable approaches, such as aerobic oxidation and visible-light-driven catalysis, aligning with green chemistry principles. Challenges, including substrate scope limitations and scalability, are addressed, along with emerging trends and future prospects for industrial and academic applications. This work aims to serve as a foundational resource for researchers exploring catalytic azo compound synthesis.