This study shows that dodecanethiolate-capped Pd nanoparticles can catalyze the conversion of propargyl alcohols to their corresponding carbonyl analogues in the presence of hydrogen gas. The stable and soluble Pd nanoparticle catalysts are prepared using sodium S-dodecylthiolsulfate as a precursor to their stabilizing ligands. The transformation involves two steps, semi-hydrogenation of alkynes and subsequent isomerization of pi-bond. The reaction conditions such as temperature, amount of hydrogen gas, and the size and composition of Pd nanoparticles are controlled for the optimization. The catalytic reactions of several propargyl alcohols including 2-propyn-1-ol, 3-butyn-2-ol, 2-butyn-1-ol, and 3-phenyl-2-propyn-1-ol are studied for understanding the effects of substituent groups. Overall the reaction produces the corresponding carbonyl compounds in good yields showing high selectivity over complete hydrogenation of alkyne functional groups. More understanding towards the catalytic activity and selectivity of alkanethiolate-capped Pd nanoparticle catalysts will increase the future applications of these new semi-heterogeneous catalysts in organic synthesis.

Tandem semi-hydrogenation and isomerization of propargyl alcohols to unsaturated carbonyl analogs catalyzed by palladium nanoparticles

243rd National Meeting (2012)

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