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<p>To comprehend the reactivity of the by-product (CF<sub>3</sub>CFCN radical) arising from the cleavage of C–CF3 bonds in heptafluoroisobutyronitrile (C<sub>3</sub>F<sub>7</sub>CN), particularly in the context of environmental concerns, we conducted an in-depth examination of its reaction mechanism with the OH radical. Employing density function theory MN15 with an augmented-cc-pVTZ level and quadratic complete basis set (CBS-QB3) methods, we explored the initial interaction between CF<sub>3</sub>CFCN radical and OH radical through two pathways: OH radical addition at the central carbon and CN carbon. These pathways lead to the formation of intermediates CF<sub>3</sub>C(OH)FCN (IM1) and CF<sub>3</sub>CFC(OH)N (IM2). Subsequently, we investigated potential isomerization pathways, including F, CF<sub>3</sub> migration and H atom shifting mechanisms. Additionally, we explored direct elimination and stepwise decomposition routes for IM1 and IM2. Our analysis identified potential toxic by-products, such as hydrogen fluoride (HF), HNC radical, cyanogen fluoride (FCN), trifluoromethane (CHF<sub>3</sub>), isocyanic acid (HNCO) and other new alkane compounds emerging from these reaction channels. Calculations of high-pressure limit rate constants were performed for the initial OH addition reaction, revealing significant product channels across a temperature range of 200–400&#xa0;K. The outcomes of our investigation underscore the pivotal role of the studied CF<sub>3</sub>CFCN radical in generating toxic species when reacting with the OH radical. Consequently, it becomes apparent that the CF<sub>3</sub>CFCN radical may serve as a specific by-product influencing the insulation breakdown of the parent C<sub>3</sub>F<sub>7</sub>CN gas in electric equipment.</p>

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Comprehensive investigation of reaction mechanism and kinetics between CF3CFCN radical and OH radical: implications for toxic species formation and electric equipment safety

  • 期刊论文

  • 发表日期：

    2025年7月7日

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  • Ponnusamy Subramani,
  • S. B. Tharchanaa

摘要

To comprehend the reactivity of the by-product (CF3CFCN radical) arising from the cleavage of C–CF3 bonds in heptafluoroisobutyronitrile (C3F7CN), particularly in the context of environmental concerns, we conducted an in-depth examination of its reaction mechanism with the OH radical. Employing density function theory MN15 with an augmented-cc-pVTZ level and quadratic complete basis set (CBS-QB3) methods, we explored the initial interaction between CF3CFCN radical and OH radical through two pathways: OH radical addition at the central carbon and CN carbon. These pathways lead to the formation of intermediates CF3C(OH)FCN (IM1) and CF3CFC(OH)N (IM2). Subsequently, we investigated potential isomerization pathways, including F, CF3 migration and H atom shifting mechanisms. Additionally, we explored direct elimination and stepwise decomposition routes for IM1 and IM2. Our analysis identified potential toxic by-products, such as hydrogen fluoride (HF), HNC radical, cyanogen fluoride (FCN), trifluoromethane (CHF3), isocyanic acid (HNCO) and other new alkane compounds emerging from these reaction channels. Calculations of high-pressure limit rate constants were performed for the initial OH addition reaction, revealing significant product channels across a temperature range of 200–400 K. The outcomes of our investigation underscore the pivotal role of the studied CF3CFCN radical in generating toxic species when reacting with the OH radical. Consequently, it becomes apparent that the CF3CFCN radical may serve as a specific by-product influencing the insulation breakdown of the parent C3F7CN gas in electric equipment.