El Hadki Hamza, Gámez Victoria Guadalupe, Dalbouha Samira, Marakchi Khadija, Kabbaj Oum Keltoum, Komiha Najia, Carvajal Miguel, Senent Diez Maria Luisa
Laboratoire de Spectroscopie, Modélisation Moléculaire, Matériaux, Nanomatériaux, Eau et Environnement, LS3MN2E/CERNE2D, Faculté des Sciences Rabat, Université Mohammed V, Rabat, BP1014, Morocco.
Departamento de Química y Física Teóricas, IEM-CSIC, Unidad Asociada GIFMAN, CSIC-UHU, Madrid, 28006, Spain.
Open Res Eur. 2022 Mar 18;1:116. doi: 10.12688/openreseurope.14073.2. eCollection 2021.
Acetone is present in the earth´s atmosphere and extra-terrestrially. The knowledge of its chemical history in these environments represents a challenge with important implications for global tropospheric chemistry and astrochemistry. The results of a search for efficient barrierless pathways producing acetone from radicals in the gas phase are described in this paper. The spectroscopic properties of radicals needed for their experimental detection are provided. The reactants were acetone fragments of low stability and small species containing C, O and H atoms. Two exergonic bimolecular addition reactions involving the radicals CH , CH CO, and CH COCH , were found to be competitive according to the kinetic rates calculated at different temperatures. An extensive spectroscopic study of the radicals CH COCH and CH CO, as well as the CH CHO isomer, was performed. Rovibrational parameters, anharmonic vibrational transitions, and excitations to the low-lying excited states are provided. For this purpose, RCCSD(T)-F12 and MRCI/CASSCF calculations were performed. In addition, since all the species presented non-rigid properties, a variational procedure of reduced dimensionality was employed to explore the far infrared region. The internal rotation barriers were determined to be V =143.7 cm (CH CO), V =3838.7 cm (CH CHO) and V =161.4 cm and V =2727.5 cm (CH COCH ).The splitting of the ground vibrational state due to the torsional barrier have been computed to be 2.997 cm , 0.0 cm , and 0.320 cm , for CH CO, CH CHO, and CH COCH , respectively. Two addition reactions, H+CH COCH and CH +CH CO, could be considered barrierless formation processes of acetone after considering all the possible formation routes, starting from 58 selected reactants, which are fragments of the molecule. The spectroscopic study of the radicals involved in the formation processes present non-rigidity. The interconversion of their equilibrium geometries has important spectroscopic effects on CH CO and CH COCH , but is negligible for CH CHO.
丙酮存在于地球大气以及地球以外的环境中。了解其在这些环境中的化学历程是一项挑战，对全球对流层化学和天体化学有着重要影响。本文描述了在气相中寻找由自由基生成丙酮的高效无势垒途径的研究结果。提供了用于实验检测的自由基的光谱性质。反应物是稳定性低的丙酮片段以及含碳、氧和氢原子的小分子。根据在不同温度下计算的动力学速率，发现涉及自由基CH、CH₃CO和CH₃COCH₂的两个放能双分子加成反应具有竞争力。对自由基CH₃COCH₂、CH₃CO以及CH₃CHO异构体进行了广泛的光谱研究。给出了振转参数、非谐振动跃迁以及到低激发态的激发情况。为此，进行了RCCSD(T)-F12和MRCI/CASSCF计算。此外，由于所有物种都呈现非刚性性质，采用了降维变分程序来探索远红外区域。确定内部旋转势垒为V = 143.7 cm⁻¹（CH₃CO）、V = 3838.7 cm⁻¹（CH₃CHO）以及V = 161.4 cm⁻¹和V = 2727.5 cm⁻¹（CH₃COCH₂）。对于CH₃CO、CH₃CHO和CH₃COCH₂，由于扭转势垒导致的基态振动能级分裂分别计算为2.997 cm⁻¹、0.0 cm⁻¹和0.320 cm⁻¹。在考虑了所有可能的生成途径后，从58种选定的反应物（即分子片段）出发，两个加成反应H + CH₃COCH₂和CH₃ + CH₃CO可被视为丙酮的无势垒生成过程。对生成过程中涉及的自由基的光谱研究表明它们具有非刚性。它们平衡几何构型的相互转化对CH₃CO和CH₃COCH₂有重要的光谱效应，但对CH₃CHO可忽略不计。
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