A highly efficient nano-sized CuO/SiO egg-shell catalyst for C-C coupling reactions.

Mesoporous SiO-supported CuO nanoparticles as an egg-shell type catalyst were prepared by impregnation method. The obtained CuO/SiO egg-shell nanocatalyst had a large surface area and narrow pore size distribution. In addition, most of the CuO nanoparticles, with sizes around 2.0 nm, were highly dispersed in the mesoporous silica. Accordingly, fast reactant diffusion to the active sites would occur, especially when the active metal sites are selectively located on the outer part of the support, , the outer region of the egg shell. In solvent-free Sonogashira reactions for the synthesis of ynones from acyl chlorides and terminal alkynes, this catalyst exhibited a very high catalytic activity. The excellent catalytic performance can be attributed to the synergistic advantages of mesoporous structure and monodispersed CuO nanoparticles.