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Gas-phase hydrogen abstraction reactions have been compared using the popular density functional theory(DFT) functional BHandHLYP/aug-cc-pVTZ/RECP level of theory,on the basis of the model reaction CHCl·-/CCl2·-+ CX3H(X = F,Cl,Br and I).Our theoretical findings suggest the efficiency of the H-abstraction reactions induced by either CHCl·-or CCl2·-increases as the substrate is changed from CF3H to CI3H,and that CHCl·-has a higher activity in hydrogen abstraction than CCl2·-for a given substrate.The entropy effect at 298 K does not significantly change the trend in reactivity of the various reactions,which is in general controlled by the heights of activation energies △E≠.Therefore,we have explored the origin of the energy barriers △E≠ of the reactions using the activation strain model of chemical reactivity.
Gas-phase hydrogen abstraction reactions have been compared using the popular density functional theory (DFT) functional BHandHLYP / aug-cc-pVTZ / RECP level of theory, on the basis of the model reaction CHCl · - / CCl2 · - + CX3H (X .Our theoretical findings suggest the efficiency of the H-abstraction reactions induced by either CHCl -or CCl2 · -increases as the substrate is changed from CF3H to CI3H, and that CHCl · -has a higher activity in hydrogen abstraction than CCl2 · -for a given substrate. entropy effect at 298 K does not significantly change the trend in reactivity of the various reactions, which is in general controlled by the heights of activation energies △ E ≠ .Therefore, we have explored the origin of the energy barriers △ E ≠ of the reactions using the activation strain model of chemical reactivity.