The oxidative reaction kinetics and mechanism of ethyl-2-methyl propionate (E2MP) and ethyl-2,2-dimethyl propionate (E22DMP) initiated by Cl atoms were investigated both experimentally and computationally. Temperature-dependent kinetic studies on the reaction of E2MP and E22DMP with Cl atoms were carried out using a relative rate technique over the temperature range of 268–363 K and at 760 Torr. The rate coefficients of both reactions at 298 K were measured (using IUPAC recommended reference rate coefficients) to be k_E2MP+Cl^298K = (7.19 ± 1.60) × 10^–11 cm³ molecule^–1 s^–1 and k_E22DMP+Cl^298K = (5.87 ± 1.33) × 10^–11 cm³ molecule^–1 s^–1, respectively. In addition to complement our experimental results, the kinetics were computed at the CCSD(T)/MG3S//BHandHLYP/6-311+G(d,p) level of theory over the temperature range of 200–400 K using the canonical variational transition state theory in conjunction with small curvature tunneling and interpolated single-point energy. Furthermore, the product degradation of the studied esters with Cl atoms was performed using gas chromatography coupled with mass spectrometry and gas chromatography coupled with infrared spectroscopy as analytical tools. The plausible product degradation mechanisms were proposed, and carbonyl compounds were found to be the major products from the degradation of studied esters. Atmospheric lifetimes of both esters were estimated with respect to the concentrations of Cl atoms in both ambient and marine boundary layer conditions.

中文翻译：

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Cl原子引发的两种生物柴油成分（2-丙酸乙酯（E2MP）和-2,2-二丙酸乙酯（E22DMP））的氧化降解动力学及其机理

通过实验和计算研究了2-甲基丙酸乙酯（E2MP）和-2,2-二甲基丙酸乙酯（E22DMP）的氧化反应动力学和机理。使用相对速率技术在268–363 K的温度范围内和760 Torr下，对E2MP和E22DMP与Cl原子的反应进行了与温度有关的动力学研究。测量两个反应在298 K时的速率系数（使用IUPAC建议的参考速率系数），_得出k _{E2MP + Cl} ^298K =（7.19±1.60）×10 ^–11 cm ³分子^–1 s ^–1和k _{E22DMP + Cl} ^298K =（5.87±1.33）×10 ^–11cm ³分子^–1 s ^–1， 分别。除了补充我们的实验结果外，还使用规范变分在200–400 K的温度范围内以CCSD（T）/ MG3S // BHandHLYP / 6-311 + G（d，p）的理论水平计算了动力学过渡态理论结合小曲率隧穿和内插单点能量。此外，使用气相色谱-质谱联用和气相色谱-红外光谱联用作为分析工具，对所研究的酯与Cl原子的产物进行降解。提出了合理的产物降解机理，发现羰基化合物是研究酯降解的主要产物。