Highly selective formation of aldehydes in the hydrogenation of the corresponding acid chlorides with silica-supported palladium catalysts prepared by a complexing agent-assisted sol–gel method

Abstract

Synthesis of aldehydes from acid chlorides was carried out using four types of supported Pd/SiO 2 catalysts, which were prepared by a complexing agent-assisted sol–gel method and two types of impregnations with organic solvents or water, and a commercial Pd/BaSO 4 catalyst. The performance of the catalysts was much affected by the catalyst preparation and activation conditions. The sol–gel catalysts activated under milder conditions exhibited the highest performance for the formation of aldehydes. The high performance of the sol–gel catalysts was due to the organic residues derived from acetylacetone and ethylene glycol used in the sol–gel catalyst preparation process. The organic residues play a role similar to that of a poison added into the reaction solution for the traditional Rosenmund reduction, while being kept in the silica gel matrices.