Nanosized metallic particles embedded in silica and carbon aerogels as catalysts in the Mizoroki-Heck coupling reaction

We have prepared silica, organic, and carbon aerogels doped with metallic Ni and Pd through sol-gel processes. Silica aerogel nanocomposites have been synthesized by impregnation, with Ni(acac)2 or Pd(acac)2, of the silica wet gels followed by ethanol supercritical drying. Organic aerogels were prepared by sol-gel copolymerization of formaldehyde with the potassium salt of 2,4-dihydroxybenzoic acid, followed by ion exchange with either Ni(NO3)2 · 6H2O or Pd(OAc) 2 and CO2 supercritical drying. No special reduction step was needed. Organic aerogels were further carbonized to obtain carbon aerogels. Pd organic and carbon aerogels containing 20-40% palladium nanoparticles are good catalysts for the Mizoroki-Heck reaction. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2005.