The gas‐phase decomposition of alkoxy radicals
The gas‐phase decomposition of alkoxy radicals
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DOI：
10.1002/kin.550110905
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发表时间：
1979-09
影响因子：
1.5
通讯作者：
L. Batt
中科院分区：
文献类型：
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作者：
L. Batt
结果表明，用一氧化氮作为自由基捕获剂，可以获得较好的烷氧基[RO]分解速率常数的数据。已经使用了两个实验系统。第一种体系使用二烷基过氧化氢[(RO)2]作为烷氧基的热源。过氧化氢浓度为∼10−4M，一氧化氮∼为2×10−4M，反应程度为∼10%。用四氟化碳作为惰性气体改变了总压。因此，机理为R2/R3=K2[NO]/K3。我们以前的研究表明，K2在1010.3±0.2M−1·s−1的范围内。第二个体系使用烷基亚硝酸盐[RONO]作为烷氧基的热源。实验条件非常相似，只是我们选择了在初始实验中使用一氧化氮气氛。如果说有什么不同的话，那就是作为一种能量转移剂，一氧化氮似乎优于四氟化碳。因此，反应机理为R3=K1‘K3[RONO]/(K3+K2+K6[NO])。给出了R=t-Am、S-Bu、t-Bu、i-Pr、Et和Me的结果。此外，还首次明确地证明了当R=t-Bu时，K_3的压力依赖性。文中还讨论了对大气化学和燃烧的影响。
It is shown that it is possible to obtain good data for the rate constant for the decomposition of alkoxy radicals [RO] by using nitric oxide as a radical trap. Two experimental systems have been used. The first system involves the use of dialkyl peroxides [(RO)2] as thermal sources of alkoxy radicals. The peroxide concentration was ∼10−4M, nitric oxide ∼2 × 10−4M, and the extent of reaction was ∼10%. The total pressure was altered using carbon tetrafluoride as an inert gas. The mechanism is Hence R2/R3 = k2[NO]/k3. Our previous studies show that k2 lies in the range 1010.3±0.2M−1·sec−1. The second system employs alkyl nitrites [RONO] as a thermal source of alkoxy radicals. The experimental conditions are very similar, except that we chose to use an atmosphere of nitric oxide for initial experiments. If anything nitric oxide appears to be superior to carbon tetrafluoride as an energy transfer agent. The mechanism is Hence R3 = k1'k3[RONO]/(k3 + k2 + k6 [NO]). Results are given for R = t-Am, s-Bu, t-Bu, i-Pr, Et, and Me. In addition the first unequivocal evidence is given for the pressure dependence of k3 when R = t-Bu. The implications for atmospheric chemistry and combustion are also discussed.