Acceptorless dehydrogenation of glycerol catalysed by Ir(III) complexes with carbohydrate‐functionalised ligands: a sweet pathway to produce hydrogen and lactic acid

Abstract

Glycerol, a by‐product of biodiesel production, has gained prominence as a precious platform chemical. To enhance the economic viability of the biodiesel production process and address the surplus of glycerol production, it is essential to transform it into value‐added products. In this context, homogeneous catalysis offers a promising avenue for glycerol valorisation. In this study, we introduce a family of iridium complexes bearing picolineamidate ligands with glucose‐functionalised substituents as novel homogeneous catalysts for glycerol to hydrogen and lactic acid conversion. These complexes exhibit high activity (conversion up to 53.3%) and 99% selectivity after 24 hours of reaction (TOFMAX=159 h‐1, TON24h=2498). Notably, the reaction occurs under ambient air and at milder temperature conditions (120°C) compared to other catalysts. These efforts in glycerol valorisation contribute to reducing biodiesel production costs, increasing the competitiveness of biofuels against petroleum‐based liquid fuels, giving rise to H2, through a global process with negative carbon dioxide emission, and lactic acid utilizable, among other, as a monomer for the synthesis of biodegradable plastics.