Citation: Chen Jie-Hao, Wang Yan, Feng Wen-Lin. Mechanism of Pyrolysis of Pyruvic Acid and Benzoylformic Acid and Calculations of Thermal Rate Constants[J]. Acta Physico-Chimica Sinica, 1999, 15(05): 431-435. doi: 10.3866/PKU.WHXB19990509
丙酮酸和苯甲酰甲酸热分解反应的速率常数
用从头算方法在6-31G的水平上研究了丙酮酸和苯甲酰甲酸热分解反应的机理．反应过程中各驻点都进行MP2相关能校准．计算结果表明：这两个反应都是羟基氢经历五元环过渡态迁移到α-羰基氧上形成氢键中间体；然后氢键中间体直接分解成异构体和二氧化碳；最后异构体经历三元环过渡态异构化成相应的醛．其中氢迁是决速步骤．在MP2／6-31G／／HF／6-31G基础上，对应于这两个反应速控步骤的活化位垒分别是186．0kJ•mol-1和169．3kJ•mol-1．在传统过渡态理论的基础上，计算了这两个反应在一定温度范围内热速率常数，理论的计算结果与实验值有很好的吻合．
English
Mechanism of Pyrolysis of Pyruvic Acid and Benzoylformic Acid and Calculations of Thermal Rate Constants
The mechanism and Kinetics for the decomposition of pyruvic acid and benzoylformic acid have been studied by using the ab initio RHF/6-31G method. The calculated activation barriers of the two reactions are 186.01 kJ•mol-1 and 169.30 kJ•mol-1 which are in reasonable agreement with the experimental data. The calculated results show that the decomposition of the two reactions is a concerted process with hydrogen transferring and bond breaking via a five-membered cyclic transition state. The thermal rate constants of the two reaction are obtained by calculating microcanonical propability fluxes through transition state, Which are fairly accurate by comparison with the experimental results.
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Key words:
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Ab initio method
- / Pyruvic acid
- / Benzoyleformic acid
- / Thermodecomposition
- / Rate constants
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