화학공학소재연구정보센터
Applied Catalysis A: General, Vol.449, 145-152, 2012
The concentration effects of reactants and components in the Pd(OAc)(2)/p-toluenesulphonic acid/trans-2,3-bis(diphenylphosphinomethyl)-norbornane catalytic system on the rate of cyclohexene hydrocarbomethoxylation
The reactants and components of a catalytic system were studied for their effects on the rate of Pd-catalysed cyclohexene hydrocarbomethoxylation. First-order reaction rate dependences were established for cyclohexene and Pd(OAc)(2), while non-monotonic rate dependences were determined for the diphosphine and p-toluenesulphonic acid concentrations and the CO pressure. The reaction was shown to follow first-order kinetics when the methanol concentration was below 0.4 mol/L; however, the reaction rate slowed upon a further increase in the methanol concentration. The obtained results were interpreted by considering a hydride mechanism supplemented with ligand exchange reactions, which decreased the activity of the catalyst, and with hydride complex annihilations by p-toluenesulphonic acid, resulting in complete loss of catalytic activity. Treatment of the proposed mechanism using the quasi-equilibrium concentration method gave a kinetic equation for the reaction that was consistent with the experimental data. (C) 2012 Elsevier B.V. All rights reserved.