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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Kinetics of the self reaction of cyclohexyl radicals
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Kinetics of the self reaction of cyclohexyl radicals

机译：环己基自由基自反应的动力学

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The kinetics of the self-reaction of cyclohexyl radicals was studied by laser photolysis/photoionization mass spectroscopy. Overall rate constants were obtained in direct real-time experiments in the temperature region 303 - 520 K and at bath gas (helium with up to 5% of radical precursors) densities (3.00-12.0)×10~(16) molecules cm~(r3). Cyclohexyl radicals were produced by a combination of the 193 nm photolysis of oxalyl chloride ((CClO)_2) with the subsequent fast reaction of Cl atoms with cyclohexane, and their initial concentrations were determined from real-time profiles of HCl. The observed overall c-C_6H_(11) + c-C _6H_(11) rate constants demonstrate negative temperature dependence, which can be described by the following expressions: k_1 = 4.8×10~(12) exp(+542 K/T) cm~3 molecule~(-1) s~(-1), with estimated uncertainty of 16% over the 303-520 K temperature range. The fraction of disproportionation equal to 41 ± 7% was determined at 305 K; analysis of earlier experimental determinations of the disproportionation-to-recombination branching ratio leads to recommending this room-temperature value for other temperatures. The corresponding temperature dependences of the recombination (1a, bicyclohexyl product) and the disproportionation (1b, cyclohexene and cyclohexane products) channels are k(1a) = 2.8×10~(-12) exp(+542 K/T) and k(1b) = 2.0×10 ~(-12) exp(+542 K/T) cm~3 molecule~(-1) s ~(-1), with estimated uncertainties of 20% and 29%, respectively.
机译：通过激光光解/光电离质谱研究了环己基自由基的自反应动力学。通过在303-520 K的温度区域和浴气体（氦气中自由基前体含量最高为5％）的密度（3.00-12.0）×10〜（16）分子cm〜（ r3）。通过193 nm草酰氯（（CClO）_2）的光解与随后的Cl原子与环己烷的快速反应相结合，产生了环己基自由基，并根据HCl的实时曲线确定了它们的初始浓度。观测到的整体c-C_6H_（11）+ cC _6H_（11）速率常数表现出负温度依赖性，可以通过以下表达式描述：k_1 = 4.8×10〜（12）exp（+542 K / T）cm〜 3分子〜（-1）s〜（-1），在303-520 K温度范围内估计不确定度为16％。在305 K下确定歧化分数等于41±7％;对歧化与重组支化比的较早实验测定的分析导致建议将该室温值推荐用于其他温度。重组（1a，双环己基产物）和歧化（1b，环己烯和环己烷产物）通道的相应温度依赖性为k（1a）= 2.8×10〜（-12）exp（+542 K / T）和k（ 1b）= 2.0×10〜（-12）exp（+542 K / T）cm〜3分子〜（-1）s〜（-1），不确定度分别为20％和29％。

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