Palladium and Copper-Catalyzed Carboxylation of Alkanes with Carbon Monoxide. Remarkable Effect of the Mixed Metal Salts

Abstract

Abstract The mixed catalyst Pd(OAc)2–Cu(OAc)2 promotes the carboxylation of cyclohexane and propane with CO in higher yield than either a Pd(II) or Cu(II) catalyst alone. The mixed catalyst has the highest activity when the ratio of Cu(II)/Pd(II) is more than unity. The carboxylations of p-xylene with Pd(II)–Cu(II) and Pd(II) afford 2,5-dimethylbenzoic acid, but no carboxylic acid is detected in the reaction with Cu(II), giving rise to p-xylene dimer as the major product instead. Clear isotope effect (3.0—3.2) is observed in the reactions of cyclohexane with Pd(II)–Cu(II) and Pd(II), unlike the reaction with Cu(II) (1.0).