Advancement in photocatalytic acceptorless dehydrogenation reactions: Opportunity and challenges for sustainable catalysis

Abstract

Dehydrogenation reactions are the challenging and thermodynamically unfavorable. Traditionally, high temperature and pressure conditions, excess of oxidants and sacrificial hydrogen acceptors are required for the dehydrogenations of various substrates, however, harsh conditions, low selectivity, and generation of large amount of organic/inorganic waste material limits the scope of these earlier developments. Introduction of light and utilisation of a photocatalyst opens the sustainable acceptorless approaches for the dehydrogenation reactions. Recently, these Photocatalytic Acceptorless Dehydrogenation (PAD) reactions have been applied to various substrates including alcohols, amines, and even more challenging inert substrates. The success of PADs for activation of low energy substrates opens the ideas for the future developments and also channelize the economical, sustainable and environment friendly approaches. Herein, we proposed a systematic review focusing on the opportunities and the challenges of these Photocatalytic Acceptorless Dehydrogenation reactions classified under homogeneous and heterogeneous catalysis sections. We have described the catalytic suitability and requirements for PAD reactions, applicability of the PAD reactions and mechanistic aspects of the developed reactions in this field. Present review targeted the hot and emerging areas on catalysis of present time and will be supportive for the related chemists exploring the sustainable developments.