Transition-metal-catalysed transfer hydrogenation using non-toxic, low cost and renewable biomass as hydrogen donors represents a sustainable and promising approach for the reduction of organic compounds. In this context, glycerol and carbohydrates are attractive hydrogen donors. In this review, we explore various catalytic systems that have been reported for reducing various unsaturated compounds, as well as the advantages and challenges associated with biomass in transfer hydrogenation reactions.

Abstract

Catalytic transfer hydrogenation is a practical approach for reduction of various unsaturated compounds and an alternative to pressurised hydrogenation and traditional metal hydride reagents. Among the various hydrogen donors, biomass such as glycerol and carbohydrates received considerable attention for the reduction reactions due to their non-toxic, eco-friendly and renewable nature. The present review addresses the development of homogeneous and heterogeneous catalysts for the transfer hydrogenation of carbonyl compounds, alkenes, alkynes, nitro compounds, CO₂ etc. using glycerol and carbohydrates as potential hydrogen donors.