The two channels of the CH(3)OH+Cl hydrogen abstraction reaction, leading to the final products CH(2)OH+HCl (i) and CH(3)O+HCl (ii), have been studied by performing ab initio MP2 calculations with the triplet split-va...The two channels of the CH(3)OH+Cl hydrogen abstraction reaction, leading to the final products CH(2)OH+HCl (i) and CH(3)O+HCl (ii), have been studied by performing ab initio MP2 calculations with the triplet split-valence polarization basis sets. For each of the two channels the following simple reaction path is predicted: reactants --> transition state --> intermediate --> products. The previously reported complicated paths(2) calculated without using the IRC technique are criticized. Our calculations indicate that channel (i) is exothermic and has a negligible energy barrier while channel (ii) is endothermic and has a substantial energy barrier. These results imply that channel (i) is favorable, which is in line with experiment.展开更多
Hydrogen abstraction reaction, H+C2H4 --H2+C2H2 was studied by using A initio SCF method. Ge-ometries were fully optimized at SCF level and energies were computed at STO-3G basis set for reactants and transition state...Hydrogen abstraction reaction, H+C2H4 --H2+C2H2 was studied by using A initio SCF method. Ge-ometries were fully optimized at SCF level and energies were computed at STO-3G basis set for reactants and transition state. Vibrational analysis was performed thereupon. Finally, the rate constant calculations were carried out at different temperatures for all range of reaction temperature according to Eyring's sbwlute reaction rate theory. The calculated activation energy is 12. 68 kcal/mol, lower than observed value (H. S kcal/mol) by 1. 82 kcal/mol only. The agreement of the calculated rate constants with the experiments is satisfactory.展开更多
The three potential surfaces for reactions of the O atom to abstract H atoms from CH2F2 and CH2Cl2 were studied using the ab initio method. The frequencies, geometries and energies of all species are calculated. The b...The three potential surfaces for reactions of the O atom to abstract H atoms from CH2F2 and CH2Cl2 were studied using the ab initio method. The frequencies, geometries and energies of all species are calculated. The best estimates of the heat of reactions are 30.92 KJ/mol and 13.01 KJ/mol, and, the best potential barrier heights for both reactions are calculated to be 74.50 KJ/mol and 67.22 KJ/mol, respectively. the second-order rate coefficients calculated are 2.8721x10(-21) and 4.2522x10(-20) cm(3)/molecule-s at 298 K, respectively.展开更多
The hydrogen abstraction reacton of F atoms with C2H2 was studied by ab initio methods at UMP2/6-31 G** level with energy gredient technique. The intrinsic reaction coordinate (IRC) of the reastion was traced by numer...The hydrogen abstraction reacton of F atoms with C2H2 was studied by ab initio methods at UMP2/6-31 G** level with energy gredient technique. The intrinsic reaction coordinate (IRC) of the reastion was traced by numerical method. Along the IRC, the coupling constants between IRC and vibrations orthogonal to it, and the vibrational frequencies were evaluated. The theoretical rate constants were calculated by the conventional transition-state theory and variational transition-state theory with tunneling correction. They were in good agreement with experimental results.展开更多
文摘The two channels of the CH(3)OH+Cl hydrogen abstraction reaction, leading to the final products CH(2)OH+HCl (i) and CH(3)O+HCl (ii), have been studied by performing ab initio MP2 calculations with the triplet split-valence polarization basis sets. For each of the two channels the following simple reaction path is predicted: reactants --> transition state --> intermediate --> products. The previously reported complicated paths(2) calculated without using the IRC technique are criticized. Our calculations indicate that channel (i) is exothermic and has a negligible energy barrier while channel (ii) is endothermic and has a substantial energy barrier. These results imply that channel (i) is favorable, which is in line with experiment.
文摘Hydrogen abstraction reaction, H+C2H4 --H2+C2H2 was studied by using A initio SCF method. Ge-ometries were fully optimized at SCF level and energies were computed at STO-3G basis set for reactants and transition state. Vibrational analysis was performed thereupon. Finally, the rate constant calculations were carried out at different temperatures for all range of reaction temperature according to Eyring's sbwlute reaction rate theory. The calculated activation energy is 12. 68 kcal/mol, lower than observed value (H. S kcal/mol) by 1. 82 kcal/mol only. The agreement of the calculated rate constants with the experiments is satisfactory.
文摘The three potential surfaces for reactions of the O atom to abstract H atoms from CH2F2 and CH2Cl2 were studied using the ab initio method. The frequencies, geometries and energies of all species are calculated. The best estimates of the heat of reactions are 30.92 KJ/mol and 13.01 KJ/mol, and, the best potential barrier heights for both reactions are calculated to be 74.50 KJ/mol and 67.22 KJ/mol, respectively. the second-order rate coefficients calculated are 2.8721x10(-21) and 4.2522x10(-20) cm(3)/molecule-s at 298 K, respectively.
基金supported by the National Natural Science Foundation of China(31271181,21263002)Natural Science Foundation of Jiangsu Province,China(BK2011811)Guangxi Natural Science Foundation,China(2013GXNSFAA019024)~~
文摘The hydrogen abstraction reacton of F atoms with C2H2 was studied by ab initio methods at UMP2/6-31 G** level with energy gredient technique. The intrinsic reaction coordinate (IRC) of the reastion was traced by numerical method. Along the IRC, the coupling constants between IRC and vibrations orthogonal to it, and the vibrational frequencies were evaluated. The theoretical rate constants were calculated by the conventional transition-state theory and variational transition-state theory with tunneling correction. They were in good agreement with experimental results.
