Photocatalytic Semi-Hydrogenation of Alkynes: A Game of Kinetics, Selectivity and Critical Timing

The semi-hydrogenation reaction of alkynes is important in the fine chemicals and pharmaceutical industries, it thus to find catalytic processes that will drive efficiently at a low cost. real challenge alkyne-to-alkene while avoiding over-hydrogenation saturated alkane moiety. problem more difficult when dealing with aromatic substitution alkyne center. Simple photocatalysts based on Palladium tend proceed alkane, stopping alkene good selectivity requires very precise timing basically no tolerance. We report here goal high conversion could be achieved TiO2-supported copper (Cu@TiO2), although slower kinetics than for Pd@TiO2. A novel bimetallic catalyst, namely, CuPd@TiO2 (0.8% Cu 0.05% Pd), methanol as hydrogen source improve by 50% respect Cu@TiO2, achieving selectivities over 95% exceptional Further, content minimizes its use, regarded an element risk depletion.