Guerrero-Méndez Luis, Lema-Saavedra Anxo, Jiménez Elena, Fernández-Ramos Antonio, Martínez-Núñez Emilio
Departamento de Química Física, Facultade de Química, Universidade de Santiago de Compostela, Avda. das Ciencias s/n 15782, Santiago de Compostela, Spain.
Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidade de Santiago de Compostela, C/Jenaro de la Fuente s/n, 15782, Santiago de Compostela, Spain.
Phys Chem Chem Phys. 2023 Aug 9;25(31):20988-20996. doi: 10.1039/d3cp02379f.
Our automated reaction discovery program, AutoMeKin, has been utilized to investigate the formation of glycolonitrile (HOCHCN) in the gas phase under the low temperatures of the interstellar medium (ISM). The feasibility of a proposed pathway depends on the absence of barriers above the energy of reactants and the availability of the suggested precursors in the ISM. Based on these criteria, several radical-radical reactions and a radical-molecule reaction have been identified as viable formation routes in the ISM. Among the radical-radical reactions, OH + CHCN appears to be the most relevant, considering the energy of the radicals and its ability to produce glycolonitrile in a single step. However, our analysis reveals that this reaction produces hydrogen isocyanide (HNC) and formaldehyde (CHO), with rate coefficients ranging from (7.3-11.5) × 10 cm molecule s across the temperature range of 10-150 K. Furthermore, the identification of this remarkably efficient pathway for HNC elimination from glycolonitrile significantly broadens the possibilities for any radical-radical mechanism proposed in our research to be considered as a feasible pathway for the formation of HNC in the ISM. This finding is particularly interesing given the persistently unexplained overabundance of hydrogen isocyanide in the ISM. Among the radical-molecule reactions investigated, the most promising one is OH + CHCHNH, which forms glycolonitrile and atomic hydrogen with rate coefficients in the range (0.3-6.6) × 10 cm molecule s within the 10-150 K temperature range. Our calculations indicate that the formation of both hydrogen isocyanide and glycolonitrile is efficient under the harsh conditions of the ISM.
我们的自动反应发现程序AutoMeKin已被用于研究星际介质（ISM）低温下气相中乙醇腈（HOCHCN）的形成。所提出途径的可行性取决于反应物能量之上不存在势垒以及ISM中建议前体的可用性。基于这些标准，已确定几种自由基 - 自由基反应和一种自由基 - 分子反应为ISM中可行的形成途径。在自由基 - 自由基反应中，考虑到自由基的能量及其一步生成乙醇腈的能力，OH + CHCN似乎是最相关的。然而，我们的分析表明，该反应生成异氰化氢（HNC）和甲醛（CHO），在10 - 150 K的温度范围内速率系数为(7.3 - 11.5)×10 cm³ molecule⁻¹ s⁻¹。此外，从乙醇腈中消除HNC的这条非常有效的途径的确定，显著拓宽了我们研究中提出的任何自由基 - 自由基机制被视为ISM中HNC形成可行途径的可能性。鉴于ISM中异氰化氢一直存在无法解释的过量现象，这一发现特别有趣。在所研究的自由基 - 分子反应中，最有前景的是OH + CHCHNH，它在10 - 150 K温度范围内以(0.3 - 6.6)×10 cm³ molecule⁻¹ s⁻¹的速率系数形成乙醇腈和原子氢。我们的计算表明，在ISM的苛刻条件下，异氰化氢和乙醇腈的形成都是有效的。
