The effects of temperature, the concentrations of methanol and the trans-2,3-bis(diphenylphosphinomethyl)norbornane (TBDPN) promoting additive on the rate of cyclohexene hydrocarbomethoxylation catalyzed by the Pd(OAc) 2 /ptoluenesulfonic acid system were studied. It was found that in the 358-383 K temperature range, the increase in the CH 3 OH concentration from 0 to 0.15 mol/L induces a virtually linear increase in the reaction rate, which slows down as the methanol concentration further increases. In the temperature range of 343-373 K, the dependences of the reaction rate on the TBDPN concentration pass through maxima at [TBDPN] = (3.0-4.0) 9 10 -3 mol/L. The results were interpreted in terms of the hydride mechanism that included diphosphinepalladium complexes as intermediates and was supplemented by ligand exchange reactions, resulting in a decrease in the activity of the palladium catalyst. The effective constants of the previously derived kinetic equation in the temperature range of 343-383 K were estimated by the least-squares method. The effective activation energies were determined and used to evaluate the enthalpy change in the ligand exchange reaction between the complexes Pd(TBDPN) 3 and [HPd(TBDPN)(CH 3 OH)]OTs. The zerovalent complex Pd(TBDPN) 3 was concluded to be more stable than the hydride complex [HPd(TBDPN)(CH 3 OH)]OTs.
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