Xu Qian, Ma Fangfang, Xia Deming, Li Xiaojing, Chen Jingwen, Xie Hong-Bin, Francisco Joseph S
Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), School of Environmental Science and Technology, Dalian University of Technology, Dalian 116024, China.
Department of Earth and Environmental Science, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6316, United States.
J Am Chem Soc. 2024 Oct 23;146(42):28866-28873. doi: 10.1021/jacs.4c09080. Epub 2024 Oct 8.
The hydrolysis of imines has long been assumed to be their main atmospheric fate, based on early studies in the field of organic chemistry. However, the hydrolysis mechanism and kinetics of atmospheric imines remain unclear. Here, an advanced Born-Oppenheimer molecular dynamics method was employed to investigate the noncatalyzed hydrolysis mechanism and kinetics at the air-water interface by selecting CHNH as a model molecule. The results indicate that CHNH exhibits a pronounced surface preference. The noncatalyzed hydrolysis of CHNH follows a unique two-step reaction mechanism involving first proton transfer and then OH transfer through the water bridge at the air-water interface, in contrast to the traditional one-step mechanism. The calculated reaction rate for the rate-determining step is 3.32 × 10 s, which is 2 orders of magnitude greater than that of the bulk phase. In addition, the involvement of the interfacial electric field further enhances the reaction rate by approximately 3 orders of magnitude. The noncatalyzed hydrolysis rate at both the air-water interface and the bulk phase is higher than that of the possible acid-catalyzed one, clarifying noncatalyzed hydrolysis as the dominant mechanism for CHNH. This study elucidates that the noncatalyzed hydrolysis of atmospheric imines is feasible at the air-water interface and that the revealed unique two-step hydrolysis mechanism has significant implications in atmospheric and water environmental chemistry.
基于有机化学领域的早期研究，长期以来人们一直认为亚胺的水解是其在大气中的主要归宿。然而，大气中亚胺的水解机制和动力学仍不清楚。在此，通过选择CHNH作为模型分子，采用先进的玻恩-奥本海默分子动力学方法研究了空气-水界面处的非催化水解机制和动力学。结果表明，CHNH表现出明显的表面偏好。与传统的一步反应机制不同，CHNH的非催化水解遵循独特的两步反应机制，首先是质子转移，然后是通过空气-水界面处的水桥进行OH转移。速率决定步骤的计算反应速率为3.32×10 s，比本体相的反应速率大2个数量级。此外，界面电场的作用使反应速率进一步提高了约3个数量级。空气-水界面和本体相的非催化水解速率均高于可能的酸催化水解速率，这表明非催化水解是CHNH的主要机制。本研究阐明了大气中亚胺在空气-水界面处的非催化水解是可行的，所揭示的独特两步水解机制在大气和水环境化学中具有重要意义。
