Heterogenous catalysis in fine chemistry:: the Heck reaction on Pd/SiO2 catalysts

The preparation conditions to obtain a Pd/SiO2 catalyst effective in the Heck reaction between para-substituted halogenobenzene and alkylacrylate have been studied. The impregnation of SiO2, functionalised with a thiourea derivative, with a Pd(CH3COO)(2) solution resulted in an active, but unstable catalyst. The catalyst became stable after calcination, but its activity appeared to be strongly dependent on the calcination temperature. IR spectra of adsorbed CO indicated that such a dependence should result from differences in the surface structure of the supported particles.