Highly efficient and recyclable ruthenium nanoparticle catalyst for semihydrogenation of alkynes

Ru nanoparticles were used as catalysts for semihydrogenation of alkynes for the first time. Poly(ethylene glycol) (PEG)-stabilized Ru nanoparticles were used as catalysts for semihydrogenation of various terminal alkynes in thermoregulated PEG biphasic system, which allows for not only an efficient homogeneous catalytic reaction, but also an easy biphasic separation and reuse of catalyst. Under the optimized conditions, various terminal alkynes were hydrogenated to the corresponding alkenes with high selectivity. After reaction, the Ru nanoparticle catalyst could be separated from products by simple phase separation and recycled for ten times without evident loss in activity and selectivity.