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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Dissociative Proton Transfer Reactions of H_3~+, N_2H~+, and H_3O~+ with Acyclic, Cyclic, and Aromatic Hydrocarbons and Nitrogen Compounds, and Astrochemical Implications
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Dissociative Proton Transfer Reactions of H_3~+, N_2H~+, and H_3O~+ with Acyclic, Cyclic, and Aromatic Hydrocarbons and Nitrogen Compounds, and Astrochemical Implications

机译：H_3〜+，N_2H〜+和H_3O〜+与无环，环和芳族碳氢化合物和氮化合物的解离质子转移反应及其天化学意义

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A flowing afterglow-selected ion flow drift tube has been used to measure the rate coefficients and product ion distributions for reactions of H_3O~+, N_2H~+, and H_3~+ with a series of 16 alkanes, alkenes, alkynes, and aromatic hydrocarbons as well as acrylonitrile, pyrrole, and pyridine. Exothermic proton transfer generally occurs close to the collision rate. The reactions of H_3O~+ are mostly nondissociative and those of H_3~+ are mostly dissociative, but many reaction, especially those of N_2H~+, have both dissociative and nondissociative channels. The dissociative channels result mostly in H_2 and/or CH_4 loss in the small hydrocarbons and in toluene, loss of C_2H_2 from acrylonitrile, and loss of HCN from pyrrole. Only nondissociative proton transfer is observed with benzene, pyridine, and larger aromatics. Drift tube studies of N_2H~+ reactions with propene and propyne showed that increased energy in the reacting ion enhances fragmentation. Some D~_3~+ reactions were also investigated and the results suggest that reactions of H_3~+ with unsaturated hydrocarbons B proceed through proton transfer that forms excited (BH~+) intermediates. Pressure effects suggest that a fraction of the (BH~+) intermediates decomposes too rapidly to allow collisional stabilization in the flow tube (t < 3 * 10~(-8) s). The other low-energy (BH~+) intermediates are formed by the removal of up to 40% of the reaction exothermicity as translational energy, and these intermediates result in stable BH~+ products. The results suggest that, in hydrogen-dominated planetary and interstellar environments, the reactions of H_3~+ can convert C_2-C_6 hydrocarbons to smaller and less saturated molecules, but polycyclic aromatics are stable against decomposition by this mechanism. The dissociative reactions of H_3~+ can therefore favor the accumulation of small unsaturated hydrocarbons and aromatics in astrochemical environments.
机译：流动的余辉选择离子流漂移管已用于测量H_3O〜+，N_2H〜+和H_3〜+与16种烷烃，烯烃，炔烃和芳烃的反应的速率系数和产物离子分布以及丙烯腈，吡咯和吡啶。放热质子转移通常发生在接近碰撞速度的地方。 H_3O〜+的反应大多是非离解性的，而H_3〜+的反应则大多是离解性的，但是许多反应，尤其是N_2H〜+的反应同时具有离解性和非离解性通道。离解通道主要导致小烃和甲苯中的H_2和/或CH_4损失，丙烯腈中的C_2H_2损失以及吡咯中的HCN损失。苯，吡啶和较大的芳烃仅观察到非解离质子转移。与丙烯和丙炔进行的N_2H〜+反应的漂移管研究表明，反应离子中能量的增加会促进碎片化。还研究了一些D〜_3〜+反应，结果表明H_3〜+与不饱和烃B的反应通过质子转移进行，形成了受激（BH〜+）中间体。压力效应表明，一部分（BH〜+）中间体分解得太快而无法在流量管中发生碰撞稳定（t <3 * 10〜（-8）s）。其他低能（BH〜+）中间体是通过去除高达40％的反应放热作为转化能而形成的，这些中间体可生成稳定的BH〜+产物。结果表明，在氢为主的行星和星际环境中，H_3〜+的反应可以将C_2-C_6烃转化为越来越少的饱和分子，但是多环芳烃对于这种分解是稳定的。因此，H_3〜+的离解反应有利于小的不饱和烃和芳烃在天化学环境中的积累。

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