了解由 OH 自由基引发的三氟氯乙烯 (CF2CFCl) 的动力学和大气降解机制,Physical Chemistry Chemical Physics

当前位置： X-MOL 学术 › Phys. Chem. Chem. Phys. › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

了解由 OH 自由基引发的三氟氯乙烯 (CF2CFCl) 的动力学和大气降解机制
Physical Chemistry Chemical Physics ( IF 2.9 ) Pub Date : 2023-04-13 , DOI: 10.1039/d3cp00161j
Saber Safari Balsini ₁ , Abolfazl Shiroudi _{1,

2} , Farhad Hatamjafari ₁ , Ehsan Zahedi ₃ , Khalil Pourshamsian ₁ , Ahmad Reza Oliaey ₁

Affiliation

使用密度泛函理论 (DFT) 研究了 OH˙ 对氯三氟乙烯 (CTFE) 的大气降解。势能面也根据从链簇 CCSD(T) 理论导出的单点能量来定义。使用M06-2x 方法在-2.62 至-0.99 kcal mol ^-1的能垒下，确定了负温度依赖性。OH˙ 攻击 C _α和 C _β原子（分别标记为路径R1和R2）表明反应R2分别为 4.22 和 4.42 kcal mol ⁻¹，比反应R1更放热和放能. 主要途径应该是将 OH˙ 添加到 β-碳中，从而产生 ˙CClF–CF ₂ OH 物种。在 298 K 时，计算出的速率常数为 9.87 × 10 ^-13 cm ³分子^-1 s ^-1。速率常数和支化比的 TST 和 RRKM 计算是在P = 1 bar 和在 250-400 K 温度范围内的下降压力状态下进行的。HF 和 ˙CClF-CFO 物种的形成通过1,2-HF 损失过程是动力学和热力学上最主要的途径。随着温度升高和压力降低，带电加合物[CTFE–OH]˙的单分子过程的区域选择性逐渐降低。与 RRKM 速率（高压极限）相比，大于 10 ^{-4巴的压力通常足以确保估计的单分子速率饱和。}_{随后的反应包括将 O 2}添加到 [CTFE–OH]˙ 加合物的 OH 基团的 α 位。[CTFE–OH–O ₂ ]˙过氧自由基主要与NO反应，然后直接分解为NO ₂和氧自由基。“氯化碳氟化物”、“碳酰氟”和“2,2-二氟-2-羟基乙酰氟”被预测为在氧化气氛中稳定的产物。

"点击查看英文标题和摘要"

Understanding the kinetics and atmospheric degradation mechanism of chlorotrifluoroethylene (CF2CFCl) initiated by OH radicals

The atmospheric degradation of chlorotrifluoroethylene (CTFE) by OH˙ was investigated using density functional theory (DFT). The potential energy surfaces were also defined in terms of single-point energies derived from the linked cluster CCSD(T) theory. With an energy barrier of −2.62 to −0.99 kcal mol⁻¹ using the M06-2x method, the negative temperature dependence was determined. The OH˙ attack on C_α and C_β atoms (labeled pathways R1 and R2, respectively) shows that reaction R2 is 4.22 and 4.42 kcal mol⁻¹, respectively, more exothermic and exergonic than reaction R1. The main pathway should be the addition of OH˙ to the β-carbon, resulting in ˙CClF–CF₂OH species. At 298 K, the calculated rate constant was 9.87 × 10⁻¹³ cm³ molecule⁻¹ s⁻¹. The TST and RRKM calculations of rate constants and branching ratios were performed at P = 1 bar and in the fall-off pressure regime over the temperature range of 250–400 K. The formation of HF and ˙CClF–CFO species via the 1,2-HF loss process is the most predominant pathway both kinetically and thermodynamically. With increasing temperature and decreasing pressure, the regioselectivity of unimolecular processes of energized adducts [CTFE–OH]˙ gradually decreases. Pressures greater than 10⁻⁴ bar are often adequate for assuring saturation of the estimated unimolecular rates when compared to the RRKM rates (in high-pressure limit). Subsequent reactions involve the addition of O₂ to the [CTFE–OH]˙ adducts at the α-position of the OH group. The [CTFE–OH–O₂]˙ peroxy radical primarily reacts with NO and then directly decomposes into NO₂ and oxy radicals. “Carbonic chloride fluoride”, “carbonyl fluoride”, and “2,2-difluoro-2-hydroxyacetyl fluoride” are predicted to be stable products in an oxidative atmosphere.

更新日期：2023-04-13

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南