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不饱和的氯氟烃可能与空气中的氧分子直接反应生成原子氧,抑制臭氧分解为氧分子和氧原子的过程进行,从而保护臭氧层。本文通过研究不饱和氯氟烃的代表物CH_2=CHF与单线态和三线态氧分子的反应机理,讨论其直接与氧分子反应生成氧原子的可能性及相关的反应和产物。在B3LYP/6-311++G(d,p)水平上,对CH_2=CHF和O_2反应及相关过程进行了计算和分析,具体包括:优化反应物、过渡态、中间体以及产物的几何构型;通过振动分析,确认过渡态、中间体以及产物;从过渡态出发进行内禀坐标(IRC)计算:反应体系中各基元反应的标准Gibbs自由能变计算;并通过零点能校正计算反应活化能。由此得出:氟乙烯与单线态氧分子反应生成的产物中有原子氧、乙酰氟、HF、CH_2=C=O、CH_3F、CO、氟乙醛,其中最稳定的产物是乙酰氟和氧原子;CH_2=CHF与氧分子反应生成抑制臭氧分解平衡的氧原子是可以自发进行的。
Unsaturated chlorofluorocarbons may react directly with the oxygen molecules in the air to generate atomic oxygen and suppress the decomposition of ozone into oxygen molecules and oxygen atoms, thereby protecting the ozone layer. In this paper, by studying the reaction mechanism of CH 2 = CHF, which is the representative of unsaturated chlorofluorocarbons, with singlet and triplet oxygen molecules, the possibility of reacting oxygen molecules directly with oxygen atoms to generate oxygen atoms and the related reactions and products are discussed. At the B3LYP / 6-311 ++ G (d, p) level, the reaction and related processes of CH_2 = CHF and O_2 were calculated and analyzed, including the optimization of reactants, transition states, intermediates and the geometries of the products The transition state, intermediates and products are confirmed by vibration analysis. The intrinsic coordinate (IRC) calculation is made from the transition state: the standard Gibbs free energy of each elementary reaction in the reaction system is calculated; and the zero point can be used to correct the calculation reaction activation energy. It is concluded that there are atomic oxygen, acetyl fluoride, HF, CH_2 = C = O, CH_3F, CO and fluoroacetaldehyde in the products of the reaction between vinyl fluoride and singlet oxygen. The most stable products are acetyl fluoride and oxygen Atoms; CH_2 = CHF reacts with oxygen molecules to generate oxygen atoms that suppress the equilibrium of ozone decomposition spontaneously.