Zhang Jia-xu, Li Ze-sheng, Liu Jing-yao, Sun Chia-Chung
Institute of Theoretical Chemistry, State Key Laboratory of Theoretical and Computational Chemistry, Jilin University, Changchun 130023, PR China.
J Phys Chem A. 2006 Mar 2;110(8):2690-7. doi: 10.1021/jp055515x.
The complex singlet potential energy surface for the reaction of CH2OH with NO2, including 14 minimum isomers and 28 transition states, is explored theoretically at the B3LYP/6-311G(d,p) and Gaussian-3 (single-point) levels. The initial association between CH2OH and NO2 is found to be the carbon-to-nitrogen approach forming an adduct HOCH2NO2 (1) with no barrier, followed by C-N bond rupture along with a concerted H-shift leading to product P1 (CH2O + trans-HONO), which is the most abundant. Much less competitively, 1 can undergo the C-O bond formation along with C-N bond rupture to isomer HOCH2ONO (2), which will take subsequent cis-trans conversion and dissociation to P2 (HOCHO + HNO), P3 (CH2O + HNO2), and P4 (CH2O + cis-HONO) with comparable yields. The obtained species CH2O in primary product P1 is in good agreement with kinetic detection in experiment. Because the intermediate and transition state involved in the most favorable pathway all lie blow the reactants, the CH2OH + NO2 reaction is expected to be rapid, as is confirmed by experiment. These calculations indicate that the title reaction proceeds mostly through singlet pathways; less go through triplet pathways. In addition, a mechanistic comparison is made with the reactions CH3 + NO2 and CH3O + NO2. The present results can lead us to deeply understand the mechanism of the title reaction and may be helpful for understanding NO2-combustion chemistry.
在B3LYP/6 - 311G(d,p)和高斯-3（单点）水平上，从理论上探索了CH2OH与NO2反应的复杂单重态势能面，其中包括14个最低能量异构体和28个过渡态。发现CH2OH与NO2最初的缔合是通过碳到氮的方式形成加合物HOCH2NO2（1），且无势垒，随后C - N键断裂并伴随协同的H迁移，生成产物P1（CH2O + 反式HONO），这是最主要的产物。竞争力小得多的是，1可以发生C - O键形成并伴随C - N键断裂生成异构体HOCH2ONO（2），其随后会进行顺反异构化和解离，生成产率相当的P2（HOCHO + HNO）、P3（CH2O + HNO2）和P4（CH2O + 顺式HONO）。在主要产物P1中得到的CH2O物种与实验中的动力学检测结果吻合良好。由于最有利反应途径中涉及的中间体和过渡态的能量均低于反应物，预计CH2OH + NO2反应会很快，实验也证实了这一点。这些计算表明，该标题反应主要通过单重态途径进行；通过三态途径的较少。此外，还与CH3 + NO2和CH3O + NO2反应进行了机理比较。目前的结果有助于我们深入理解该标题反应的机理，并可能有助于理解NO2燃烧化学。
