Efficient partial hydrogenation of 2-butyne-1,4-diol and other alkynes under microwave irradiation

Abstract The microwave-assisted partial hydrogenation of 2-butyne-1,4-diol, diphenylacetylene and phenylacetylene with novel lead-free Pd/Boehmite catalysts were investigated. Obtaining high alkyne conversion and good selectivity of the product alkenes required optimization of several reaction parameters: substrate concentration, amount of catalyst, temperature, hydrogen pressure, solvent and reaction scale. Dielectric heating strongly enhanced the conversion whilst maintaining good selectivity to alkenes (over 92%). Excellent 2-butyne-1,4-diol conversions, with 100% alkene selectivity, were achieved in water (20 mL) at 90 °C at high substrate concentrations (20 wt%).