| Ab initio study on the mechanism of reaction HNCO+NH_2 |
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| 引用本文： | 冀永强,冯文林,徐振峰,雷鸣. Ab initio study on the mechanism of reaction HNCO+NH_2[J]. 中国科学B辑(英文版), 2002, 45(4) |
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| 作者姓名： | 冀永强 冯文林 徐振峰 雷鸣 |
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| 作者单位： | Jl Yongqiang，FENG Wenlin XU Zhenfeng& LEI MingDepartment of Chemistry，Faculty of Science，Beijing University of Chemical Technology，Beijing 100029，China |
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| 基金项目： | This work was supported by (he Research Fund of Ministry of Education for Academic Institutionof Doctoral Education (Grant No. 1999002715)，Investigation Fund of Committee of Education of Ningxia Hui Autonomous Region. |
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| 摘 要： | Ab initio UMP2 and UQCISD(T) calculations, with 6-311G** basis sets, were performed for the titled reactions. The results show that the reactions have two product channels: NH2+ HNCO→NH3+NCO (1) and NH2+HNCO-N2H3+CO (2), where reaction (1) is a hydrogen abstraction reaction via an H-bonded complex (HBC), lowering the energy by 32.48 kJ/mol relative to reactants. The calculated QCISD(T)//MP2(full) energy barrier is 29.04 kJ/mol, which is in excellent accordance with the experimental value of 29.09 kJ/mol. In the range of reaction temperature 2300-2700 K, transition theory rate constant for reaction (1) is 1.68 × 1011- 3.29 × 1011 mL · mol-1· s-1, which is close to the experimental one of 5.0 ×1011 mL× mol-1· s-1 or less. However, reaction (2) is a stepwise reaction proceeding via two orientation modes, cis and trans, and the energy barriers for the rate-control step at our best calculations are 92.79 kJ/mol (for cis-mode) and 147.43 kJ/mol (for trans-mode), respectively, which is much higher than
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Ab initio study on the mechanism of reaction HNCO+NH2 |
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| Jl Yongqiang,FENG Wenlin XU Zhenfeng, LEI Ming. Ab initio study on the mechanism of reaction HNCO+NH2[J]. Science in China(Chemistry), 2002, 45(4) |
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| Authors: | Jl Yongqiang FENG Wenlin XU Zhenfeng& LEI Ming |
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| Affiliation: | Department of Chemistry, Faculty of Science, Beijing University of Chemical Technology, Beijing 100029, China |
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| Abstract: | Ab initio UMP2 and UQCISD(T) calculations, with 6-311G** basis sets, were performed for the titled reactions. The results show that the reactions have two product channels: NH2+HNCO→NH3+NCO (1) and NH2+HNCO→N2H3+CO (2), where reaction (1) is a hydrogen abstraction reaction via an H-bonded complex (HBC), lowering the energy by 32.48 kJ/mol relative to reactants. The calculated QCISD(T)//MP2(full) energy barrier is 29.04 kJ/mol, which is in excellent accordance with the experimental value of 29.09 kJ/mol. In the range of reaction temperature 2300-2700 K, transition theory rate constant for reaction (1) is 1.68×1011-3.29×1011 mL@mol?1@s?1, which is close to the experimental one of 5.0×1011 mL@mol?1@s?1 or less. How- ever, reaction (2) is a stepwise reaction proceeding via two orientation modes, cis and trans, and the energy barriers for the rate-control step at our best calculations are 92.79 kJ/mol (for cis-mode) and 147.43 kJ/mol (for trans-mode), respectively, which is much higher than reaction (1). So reaction (1) is the main channel for the titled reactions. |
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| Keywords: | isocyanic acid radical reaction ab initio method hydrogen-bonded complex. |
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