在297 - 526K温度下，氮气/氧气稀释剂中氯与丁酮反应的产物及反应机理。
Products and mechanism of the reaction of Cl with butanone in N2/O2 diluent at 297-526 K.
作者信息
Kaiser E W, Wallington T J, Hurley M D
机构信息
Department of Natural Sciences, University of Michigan Dearborn, 4901 Evergreen Road, Dearborn, Michigan 48128, USA.
出版信息
J Phys Chem A. 2009 Mar 19;113(11):2424-37. doi: 10.1021/jp809169h.
The products, kinetics, and mechanism of the reaction Cl + butanone have been measured by UV irradiation of Cl(2)/butanone/N(2) (O(2)) mixtures using either GC or FTIR analysis. In the absence of O(2), the products are 1-, 3-, and 4-chlorobutanone with yields of 3.1%, 76%, and 22.5%, respectively. As the temperature is increased, the yields of 1- and 4-chlorobutanone increase relative to the 3-chlorobutanone yield. On the basis of these increases, the activation energies for hydrogen abstraction at the 1 and 4 positions are determined to be 1800 (+/-300) and 470 (+300, -150) cal mol(-1) relative to abstraction at the 3 position. In the presence of 400 ppm of O(2) with 700-900 ppm of Cl(2) at 297 K, the yields of 1- and 3-chlorobutanone decrease dramatically from 3.1% to 0.25% and from 76% to 2%, respectively, while the 4-chlorobutanone decreases only slightly from 22.5% to 18.5%. The observed oxygenated species are acetaldehyde (52%), butanedione (11%), and propionyl chloride (2.5%). Increasing the temperature to 400 K (O(2) = 500 ppm) suppresses these oxygenated products and 1- and 3-chlorobutanone again become the primary products, indicating that the O(2) addition reaction to the 1- and 3-butanonyl radicals is becoming reversible. At 500 K and very high O(2) mole fraction (170,000 ppm), a new product channel opens which forms a substantial yield (approximately 20%) of methylvinylketone. Computer modeling of the product yields has been performed to gain an understanding of the overall reaction mechanism in the presence and absence of O(2). The reaction of chlorine atoms with butanone proceeds with a rate constant of 4.0 (+/-0.4) x 10(-11) cm(3) molecule(-1) s(-1) independent of temperature over the range 297-475 K (E(a) = 0 +/- 200 cal mol(-1)). Rate constant ratios of k(CH(2)C(O)C(2)H(5) + Cl(2))/k(CH(2)C(O)C(2)H(5) + O(2)) = 0.027 +/- 0.008, k(CH(3)C(O)CHCH(3) + Cl(2))/ k(CH(3)C(O)CHCH(3) + O(2)) = 0.0113 +/- 0.0011, and k(CH(3)C(O)CH(2)CH(2) + Cl(2))/k(CH(3)C(O)CH(2)CH(2) + O(2)) = 1.52 +/- 0.32 were determined at 297 K in 800-950 Torr of N(2) diluent. In 700-900 Torr of N(2)/O(2) diluent, the major fate of the alkoxy radicals CH(3)C(O)CH(O)CH(3) and OCH(2)C(O)C(2)H(5) is decomposition to give CH(3)C(O) radicals and CH(3)CHO and HCHO and C(O)C(2)H(5) radicals, respectively.
通过使用气相色谱（GC）或傅里叶变换红外光谱（FTIR）分析，对Cl₂/丁酮/N₂（O₂）混合物进行紫外线照射，测量了Cl与丁酮反应的产物、动力学和反应机理。在没有O₂的情况下，产物为1-氯丁酮、3-氯丁酮和4-氯丁酮，产率分别为3.1%、76%和22.5%。随着温度升高，1-氯丁酮和4-氯丁酮的产率相对于3-氯丁酮的产率增加。基于这些增加，相对于在3位的氢提取，在1位和4位进行氢提取的活化能分别确定为1800（±300）和470（+300，-150）cal mol⁻¹。在297K下，当存在400ppm的O₂和700 - 900ppm的Cl₂时，1-氯丁酮和3-氯丁酮的产率分别从3.1%急剧下降到0.25%，从76%下降到2%，而4-氯丁酮仅从22.5%略微下降到18.5%。观察到的含氧化合物是乙醛（52%）、丁二酮（11%）和丙酰氯（2.5%）。将温度升高到400K（O₂ = 500ppm）会抑制这些含氧化合物产物，1-氯丁酮和3-氯丁酮再次成为主要产物，这表明O₂与1-和3-丁酰基自由基的加成反应变得可逆。在500K和非常高的O₂摩尔分数（170,000ppm）下，一个新的产物通道打开，形成大量产率（约20%）的甲基乙烯基酮。已对产物产率进行计算机建模，以了解在有O₂和无O₂情况下的整体反应机理。氯原子与丁酮的反应速率常数为4.0（±0.4）×10⁻¹¹ cm³·分子⁻¹·s⁻¹，在297 - 475K范围内与温度无关（Eₐ = 0 ± 200 cal mol⁻¹）。在297K、800 - 950托的N₂稀释剂中，确定了速率常数比k(CH₂C(O)C₂H₅ + Cl₂)/k(CH₂C(O)C₂H₅ + O₂) = 0.027 ± 0.008、k(CH₃C(O)CHCH₃ + Cl₂)/k(CH₃C(O)CHCH₃ + O₂) = 0.0113 ± 0.0011和k(CH₃C(O)CH₂CH₂ + Cl₂)/k(CH₃C(O)CH₂CH₂ + O₂) = 1.52 ± 0.32。在700 - 900托的N₂/O₂稀释剂中，烷氧基自由基CH₃C(O)CH(O)CH₃和OCH₂C(O)C₂H₅的主要命运分别是分解生成CH₃C(O)自由基和CH₃CHO以及HCHO和C(O)C₂H₅自由基。
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