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首页> 外文期刊>ACS Omega >Theoretical Study of the Kinetics of the Gas-Phase Reaction between Phenyl and Amino Radicals
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Theoretical Study of the Kinetics of the Gas-Phase Reaction between Phenyl and Amino Radicals

机译：苯基与氨基自由基气相反应动力学的理论研究

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The potential energy surface (PES) of the C6H5 + NH2 reaction has been investigated by using ab initio CCSD(T)//B3LYP/6-311++G(3df,2p) calculations. The conventional transition-state theory (TST) and the variable reaction coordinate-TST (VRC-TST) have been used to predict the rate constants for the channels possessing tight and barrierless transition states, respectively. The Rice–Ramsperger–Kassel–Marcus/Master equation (RRKM/ME) theory has been utilized to determine the pressure-dependent rate constants for these reactions. The PES shows that the reaction begins with an exothermic barrierless addition of NH2 to C6H5 producing the vital intermediate state, namely, aniline (C6H5NH2, IS1). Once IS1 is generated, it can further isomerize to various intermediate states, which can give rise to different products, including PR4 (4,5,6-trihydro-1-amino phenyl + H2), PR5 (3,4,5,6-tetrahydro phenyl + NH3), PR6 (2,3,5,6-tetrahydro-1-imidogen phenyl + H2), PR9 (3,4,5,6-tetrahydro-1-imidogen phenyl + H2), and PR10 (2,5,6-trihydro-1-amino phenyl + H2), of which the most stable product, PR5, was formed by the most favorable channel going through the two advantageous transition states T1/11 (?28.9 kcal/mol) and T11P5 (?21.5 kcal/mol). The calculated rate constants for the low-energy channel, 1.37 × 10–9 and 2.16 × 10–11 cm3 molecule–1 s–1 at T = 300, P = 1 Torr and T = 2000 K, P = 760 Torr, respectively, show that the title reaction is almost pressure- and temperature-dependent. The negative temperature-dependent rate coefficients can be expressed in the modified Arrhenius form of k1 = 8.54 × 1013T–7.20 exp?(?7.07 kcal·mol–1/RT) and k2 = 2.42 × 1015T–7.61 exp?(?7.75 kcal·mol–1/RT) at 1 and 10 Torr, respectively, and in the temperature range of 300–2000 K. The forward and reverse rate coefficients as well as the high-pressure equilibrium constants of the C6H5 + NH2 ? IS1 process were also predicted; their values revealed that its kinetics do not depend on pressure at low temperature but strongly depend on pressure at high temperature. Moreover, the predicted formation enthalpies of reactants and the enthalpy changes of some channels are in good agreement with the experimental results.
机译：通过使用从头开始的CCSD（T）// B3LYP / 6-311 ++ G（3df，2p）计算，研究了C6H5 + NH2反应的势能面（PES）。常规的过渡态理论（TST）和可变反应坐标-TST（VRC-TST）已分别用于预测具有紧密和无障碍过渡态的通道的速率常数。 Rice-Ramsperger-Kassel-Marcus / Master方程（RRKM / ME）理论已用于确定这些反应的压力相关速率常数。 PES表明，该反应始于向C6H5放热无障碍添加NH2，从而产生重要的中间体状态，即苯胺（C6H5NH2，IS1）。生成IS1后，它可以进一步异构化为各种中间状态，从而产生不同的产物，包括PR4（4,5,6-三氢-1-氨基苯基+ H2），PR5（3,4,5,6 -四氢苯基+ NH3），PR6（2,3,5,6-四氢-1-酰亚胺基苯基+ H2），PR9（3,4,5,6-四氢-1-酰亚胺基苯基+ H2）和PR10（ 2,5,6-三氢-1-氨基苯基+ H2），其中最稳定的产物PR5是通过穿过两个有利的过渡态T1 / 11（？28.9 kcal / mol）和T11P5（〜21.5kcal / mol）。低能量通道的计算常数为1.37×10–9和2.16×10–11 cm3分子–1 s–1，分别位于T = 300，P = 1 Torr和T = 2000 K，P = 760 Torr时，表明标题反应几乎与压力和温度有关。负温度依赖的速率系数可以用修正的Arrhenius形式表示，k1 = 8.54×1013T–7.20 exp？（？7.07 kcal·mol–1 / RT），k2 = 2.42×1015T–7.61 exp？（？7.75 kcal） ·mol–1 / RT）分别在1和10 Torr以及300–2000 K的温度范围内。C6H5 + NH2的正向和反向速率系数以及高压平衡常数？还预测了IS1流程;它们的值表明，其动力学不取决于低温下的压力，而很大程度上取决于高温下的压力。而且，预测的反应物生成焓和某些通道的焓变与实验结果吻合良好。

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