Acid‐ and Base‐Catalyzed Hydrolytic Hydrogen Evolution from Diboronic Acid

The efficient production of H-2 from hydrogen-rich sources, particularly from water, is a crucial task and a great challenge, both as a sustainable energy source and on the laboratory scale for hydrogenation reactions. Herein, a facile and effective synthesis of H-2 and D-2 from only acid- or base-catalyzed metal-free hydrolysis of B-2(OH)(4), a current borylation reagent, has been developed without any transition metal or ligand. Acid-catalyzed H-2 evolution was completed in 4 min, whereas the base-catalyzed process needed 6 min. The large kinetic isotopic effects for this reaction with D2O, deuteration experiments and mechanistic studies have confirmed that both H atoms of H-2 originate from water using either of these reactions. This new, metal-free catalytic system holds several advantages, such as high efficiency, simplicity of operation, sustainability, economy, and potential further use.