The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optim...The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optimized at HF/LANL2DZ level under the ECP approximation. The potential energy profiles for elementary reactions of carbonylation are calculated respectively. The transition states are further confirmed by having one and only one imaginary vibrational frequency. The results indicate that the activation energy values of CHin3I oxidative addition, carbonyl insertion and CH3COI reductive elimination fundamental steps are 216.03, 128.10 and 126.55 kJ/mol, respectively; and that the CH3I oxidative addition step is predicted to be the rate-determining one.展开更多
A general theory of Van der Waals forces developed by Lifshitz based on quantum electrodynamics theory is applied in the range R?λ0( where the Casimir effects may be neglected) to construct Van der Waals attractive p...A general theory of Van der Waals forces developed by Lifshitz based on quantum electrodynamics theory is applied in the range R?λ0( where the Casimir effects may be neglected) to construct Van der Waals attractive potential between identical dielectric molecules in rarefied media in order that the effective attractive potential between the like-molecules (including the repeat units) is offered. A closed form solution for the integral formulation of the attractive potential between like-particles is first obtained based on certain assumptions made in this work. On the basis of the theory of electric polarization, the derived expression in terms of bulk properties is then compared with the well-known London formula, the former differs from the latter only by the fact $\frac{4}{\pi }or\frac{4}{\pi }\left( {\frac{{\varepsilon _\infty + 2}}{3}} \right)^2 $ The validity of the effective potential can be verified by testing cases composed of several types of dielectric materials. The computed results are presented in this paper, and comparisons with the results computed by London dispersion formula, as well as the recommended values in virtue of the experimental and theoretical techniques, are also presented. The effective potential of polyethylene is also computed to demonstrate the effectiveness of the developed model, and it is found that the computed well depth fall within a reasonable range of accuracy.展开更多
基金the Young Teachers' Foundation of Beijing University of Chemical Technology (Grant No. QN0018).
文摘The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optimized at HF/LANL2DZ level under the ECP approximation. The potential energy profiles for elementary reactions of carbonylation are calculated respectively. The transition states are further confirmed by having one and only one imaginary vibrational frequency. The results indicate that the activation energy values of CHin3I oxidative addition, carbonyl insertion and CH3COI reductive elimination fundamental steps are 216.03, 128.10 and 126.55 kJ/mol, respectively; and that the CH3I oxidative addition step is predicted to be the rate-determining one.
基金This work was supported by the National Natural Science Foundation of China (Grant No. 19682002) .
文摘A general theory of Van der Waals forces developed by Lifshitz based on quantum electrodynamics theory is applied in the range R?λ0( where the Casimir effects may be neglected) to construct Van der Waals attractive potential between identical dielectric molecules in rarefied media in order that the effective attractive potential between the like-molecules (including the repeat units) is offered. A closed form solution for the integral formulation of the attractive potential between like-particles is first obtained based on certain assumptions made in this work. On the basis of the theory of electric polarization, the derived expression in terms of bulk properties is then compared with the well-known London formula, the former differs from the latter only by the fact $\frac{4}{\pi }or\frac{4}{\pi }\left( {\frac{{\varepsilon _\infty + 2}}{3}} \right)^2 $ The validity of the effective potential can be verified by testing cases composed of several types of dielectric materials. The computed results are presented in this paper, and comparisons with the results computed by London dispersion formula, as well as the recommended values in virtue of the experimental and theoretical techniques, are also presented. The effective potential of polyethylene is also computed to demonstrate the effectiveness of the developed model, and it is found that the computed well depth fall within a reasonable range of accuracy.
