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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Intramolecular Hydrogen Shift Chemistry of Hydroperoxy-Substituted Peroxy Radicals
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Intramolecular Hydrogen Shift Chemistry of Hydroperoxy-Substituted Peroxy Radicals

机译：硫代氧基取代过氧基质的分子内氢变化化学

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Gas-phase autoxidation - the sequential regeneration of peroxy radicals (RO2) via intramolecular hydrogen shifts (H-shifts) followed by oxygen addition - leads to the formation of organic hydroperoxides. The atmospheric fate of these peroxides remains unclear, including the potential for further H-shift chemistry. Here, we report H-shift rate coefficients for a system of RO2 with hydroperoxide functionality produced in the OH-initiated oxidation of 2-hydroperoxy-2-methylpentane. The initial RO2 formed in this chemistry are unable to undergo alpha-OOH H-shift (HOOC-H) reactions. However, these RO2 rapidly isomerize (100 s(-1) at 296 K) by H-shift of the hydroperoxy hydrogen (ROO-H) to produce a hydroperoxy-substituted RO2 with an accessible alpha-OOH hydrogen. First order rate coefficients for the 1,5 H-shift of the alpha-OOH hydrogen are measured to be similar to 0.04 s(-1) (296 K) and similar to 0.1 s(-1) (318 K), within 50% of the rate coefficients calculated using multiconformer transition state theory. Reaction of the RO2 with NO produces alkoxy radicals which also undergo rapid isomerization via 1,6 and 1,5 H-shift of the hydroperoxy hydrogen (ROO-H) to produce RO2 with alcohol functionality. One of these hydroxy-substituted RO2 exhibits a 1,5 alpha-OH (HOC-H) H-shift, measured to be similar to 0.2 s(-1) (296 K) and similar to 0.6 s(-1) (318 K), again in agreement with the calculated rates. Thus, the rapid shift of hydroperoxy hydrogens in alkoxy and peroxy radicals enables intramolecular reactions that would otherwise be inaccessible.
机译：气相自氧化 - 过氧自由基（RO2）通过分子内氢变换（H型偏移）的顺序再生，然后加入氧气 - 导致有机氢过氧化物的形成。这些过氧化物的大气命运仍不清楚，包括进一步的H移位化学的潜力。这里，我们报告HO 2系统的H移位率系数，其具有在OH-氧化的2-氢过氧氢-2-甲基戊烷的OH-发起的氧化中产生的氢过氧化物官能团。在该化学中形成的初始RO2不能经历α-OOH H型偏移（HOOC-H）反应。然而，通过氢过氧化氢（ROO-H）的H型偏移，这些RO2快速异构化（在296 k处以296 k），用可接近的α-oOH氢气制备氢过氧基取代的RO2。测量α-OOH氢气的1.5升偏移的第一阶速率系数与0.04 s（-1）（296k）相似，类似于0.1s（-1）（318 k），在50内使用多电机转换状态理论计算的速率系数的百分比。 RO 2的反应不会产生烷氧基，该烷氧基也经过氢化氢氢（ROO-H）的1,6和1.5 H型偏移快速异构化，以产生具有醇官能度的RO2。这些羟基取代的RO2中的一种表现出1.5α-OH（HOC-H）H型偏移，以类似于0.2S（-1）（296k），类似于0.6 s（-1）（318 k），再次与计算的速率同意。因此，烷氧基和过氧基团中的氢过氧化氢的快速变化使分子内反应能够难以接近。

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