Synthesis of carbon encapsulated metal (Ni and Cu) nano particles and applications for chiral catalysts

摘要

Carbon-encapsulated Ni and Cu nanoparticles with a core/shell structure were synthesized by levitational gas condensation (LGC). Methane (CH_4) gas was used to coat the surface of the Ni and Cu nanoparticles. The Ni particles had a core diameter of 10 nm, and were covered by 2-3 nm thin carbon layers. In the case of Cu, the particles had a core diameter of 30 nm, and multi-shells with a thickness of 2-3 nm. Biginelli reaction in the presence of L-proline and Ni encapsulated nanoparticles was carried out to change the ratio between stereoisomers in favor of the S-enantiomer for 3,4—dihydropyrimidine (DHPM) with an excess of about 18%.