丙酮酰过氧和氢过氧的自反应及交叉反应：温度依赖性动力学参数、支化分数和伴随效应
Acetonyl Peroxy and Hydroperoxy Self- and Cross-Reactions: Temperature-Dependent Kinetic Parameters, Branching Fractions, and Chaperone Effects.
作者信息
Zuraski Kristen, Grieman Fred J, Hui Aileen O, Cowen Julia, Winiberg Frank A F, Percival Carl J, Okumura Mitchio, Sander Stanley P
机构信息
NASA Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109, United States.
Seaver Chemistry Laboratory, Pomona College, Claremont, California 91711, United States.
出版信息
J Phys Chem A. 2023 Sep 21;127(37):7772-7792. doi: 10.1021/acs.jpca.3c03660. Epub 2023 Sep 8.
The temperature-dependent kinetic parameters, branching fractions, and chaperone effects of the self- and cross-reactions between acetonyl peroxy (CHC(O)CHO) and hydro peroxy (HO) have been studied using pulsed laser photolysis coupled with infrared (IR) wavelength-modulation spectroscopy and ultraviolet absorption (UVA) spectroscopy. Two IR lasers simultaneously monitored HO and hydroxyl (OH), while UVA measurements monitored CHC(O)CHO. For the CHC(O)CHO self-reaction ( = 270-330 K), the rate parameters were determined to be = (1.5) × 10 and / = -996 ± 334 K and the branching fraction to the alkoxy channel, /, showed an inverse temperature dependence following the expression, / = (2.27 ± 0.62) - [(6.35 ± 2.06) × 10] (K). For the reaction between CHC(O)CHO and HO ( = 270-330 K), the rate parameters were determined to be = (3.4) × 10 and / = -547 ± 415 K for the hydroperoxide product channel and = (6.23) × 10 and / = -3100 ± 870 K for the OH product channel. The branching fraction for the OH channel, /, follows the temperature-dependent expression, / = (3.27 ± 0.51) - [(9.6 ± 1.7) × 10] (K). Determination of these parameters required an extensive reaction kinetics model which included a re-evaluation of the temperature dependence of the HO self-reaction chaperone enhancement parameters due to the methanol-hydroperoxy complex. The second-law thermodynamic parameters for for the formation of the complex were found to be Δ = -38.6 ± 3.3 kJ mol and Δ = -110.5 ± 13.2 J mol K, with the third-law analysis yielding Δ = -37.5 ± 0.25 kJ mol. The HO self-reaction rate coefficient was determined to be = (3.34) × 10 exp [(507 ± 76)/]cm molecule s with the enhancement term = (2.7) × 10 exp [(4700 ± 255)/]cm molecule s, proportional to [CHOH], over = 220-280 K. The equivalent chaperone enhancement parameter for the acetone-hydroperoxy complex was also required and determined to be = (5.0 × 10 - 1.4 × 10) exp[(7396 ± 1172)/] cm molecule s, proportional to [CHC(O)CH], over = 270-296 K. From these parameters, the rate coefficients for the reactions between HO and the respective complexes over the given temperature ranges can be estimated: for HO·CHOH, = [(1.72 ± 0.050) × 10] exp [(314 ± 7.2)/T] cm molecule s and for HO·CHC(O)CH, = [(7.9 ± 0.72) × 10] exp [(3881 ± 25)/] cm molecule s. Lastly, an estimate of the rate coefficient for the HO·CHOH self-reaction was also determined to be = (1.3 ± 0.45) × 10 cm molecule s.
利用脉冲激光光解结合红外（IR）波长调制光谱和紫外吸收（UVA）光谱，研究了丙酮酰过氧自由基（CHC(O)CHO）与氢过氧自由基（HO）之间自反应和交叉反应的温度相关动力学参数、分支比和伴随效应。两台红外激光器同时监测HO和羟基自由基（OH），而UVA测量则监测CHC(O)CHO。对于CHC(O)CHO自反应（T = 270 - 330 K），确定速率参数为k = (1.5) × 10⁻¹² cm³ molecule⁻¹ s⁻¹，Eₐ/RT = -996 ± 334 K，且通向烷氧基通道的分支比kₐ/k显示出反温度依赖性，符合表达式kₐ/k = (2.27 ± 0.62) - [(6.35 ± 2.06) × 10⁻³]T (K)。对于CHC(O)CHO与HO之间的反应（T = 270 - 330 K），对于氢过氧化物产物通道，确定速率参数为k = (3.4) × 10⁻¹² cm³ molecule⁻¹ s⁻¹，Eₐ/RT = -547 ± 415 K；对于OH产物通道，k = (6.23) × 10⁻¹² cm³ molecule⁻¹ s⁻¹，Eₐ/RT = -3100 ± 870 K。OH通道的分支比kₒ/k遵循温度相关表达式kₒ/k = (3.27 ± 0.51) - [(9.6 ± 1.7) × 10⁻³]T (K)。确定这些参数需要一个广泛的反应动力学模型，该模型包括由于甲醇 - 氢过氧复合物对HO自反应伴随增强参数的温度依赖性进行重新评估。发现该复合物形成的第二定律热力学参数为ΔH = -38.6 ± 3.3 kJ mol⁻¹，ΔS = -110.5 ± 13.2 J mol⁻¹ K⁻¹，第三定律分析得出ΔH = -37.5 ± 0.25 kJ mol⁻¹。确定HO自反应速率系数为k = (3.34) × 10⁻¹² exp [(507 ± 76)/T] cm³ molecule⁻¹ s⁻¹，增强项kₑ = (2.7) × 10⁻¹² exp [(4700 ± 255)/T] cm³ molecule⁻¹ s⁻¹，与[CH₃OH]成正比，在T = 220 - 280 K范围内。还需要丙酮 - 氢过氧复合物的等效伴随增强参数，并确定为kₑ = (5.0 × 10⁻¹³ - 1.4 × 10⁻¹³) exp[(7396 ± 1172)/T] cm³ molecule⁻¹ s⁻¹，与[CH₃C(O)CH₃]成正比，在T = 270 - 296 K范围内。根据这些参数，可以估计在给定温度范围内HO与相应复合物之间反应的速率系数：对于HO·CH₃OH，k = [(1.72 ± 0.050) × 10⁻¹²] exp [(314 ± 7.2)/T] cm³ molecule⁻¹ s⁻¹；对于HO·CH₃C(O)CH₃，k = [(7.9 ± 0.72) × 10⁻¹²] exp [(3881 ± 25)/T] cm³ molecule⁻¹ s⁻¹。最后，还确定HO·CH₃OH自反应速率系数的估计值为k = (1.3 ± 0.45) × 10⁻¹³ cm³ molecule⁻¹ s⁻¹。
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