Kinetics and Mechanisms of the Allyl + Allyl and Allyl + Propargyl Recombination Reactions

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• 作者：Akira Matsugi ; Kohsuke Suma ; Akira Miyoshi
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：July 7, 2011
• 年：2011
• 卷：115
• 期：26
• 页码：7610-7624
• 全文大小：1260K
• 年卷期：v.115,no.26(July 7, 2011)
• ISSN：1520-5215

文摘

The kinetics and mechanisms of the self-reaction of allyl radicals and the cross-reaction between allyl and propargyl radicals were studied both experimentally and theoretically. The experiments were carried out over the temperature range 295鈥?00 K and the pressure range 20鈥?00 Torr (maintained by He or N₂). The allyl and propargyl radicals were generated by the pulsed laser photolysis of respective precursors, 1,5-hexadiene and propargyl chloride, and were probed by using a cavity ring-down spectroscopy technique. The temperature-dependent absorption cross sections of the radicals were measured relative to that of the HCO radical. The rate constants have been determined to be k(C₃H₅ + C₃H₅) = 1.40 脳 10^鈥?T^鈥?.933 exp(鈭?25/T) cm³ molecule^鈥? s^鈥? (螖 log₁₀k = 卤 0.088) and k(C₃H₅ + C₃H₃) = 1.71 脳 10^鈥?T^鈥?.182 exp(鈭?55/T) cm³ molecule^鈥? s^鈥? (螖 log₁₀k = 卤 0.069) with 2蟽 uncertainty limits. The potential energy surfaces for both reactions were calculated with the CBS-QB3 and CASPT2 quantum chemical methods, and the product channels have been investigated by the steady-state master equation analyses based on the Rice鈥揜amsperger鈥揔assel鈥揗arcus theory. The results indicated that the reaction between allyl and propargyl radicals produces five-membered ring compounds in combustion conditions, while the formations of the cyclic species are unlikely in the self-reaction of allyl radicals. The temperature- and pressure-dependent rate constant expressions for the important reaction pathways are presented for kinetic modeling.