Unusual Diradical Intermediates in Ozonolysis of Alkenes: A Combined Theoretical and Synchrotron Radiation Photoionization Mass Spectrometric Study on Ozonolysis of Alkyl Vinyl Ethers
Unusual Diradical Intermediates in Ozonolysis of Alkenes: A Combined Theoretical and Synchrotron Radiation Photoionization Mass Spectrometric Study on Ozonolysis of Alkyl Vinyl Ethers
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DOI：
10.1021/acs.jpca.2c04382
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发表时间：
2022-10-19
影响因子：
2.9
通讯作者：
Wang，Liming
中科院分区：
文献类型：
--
作者：
Fan，Hanlin;Ma，Jun;Wang，Liming
对乙基乙烯醚（EVE）和丁基乙烯醚的臭氧分解进行了计算和实验，确定了一种由原生臭氧的O-O键裂解产生的非常规二自由基中间体。双自由基可以经历H原子转移过程，产生酮-氢过氧化物（KHP），这是识别双自由基中间体存在的特征产物。RRKM-ME计算基于CCSD(T)/VTZ//M06-2X/6-311++G（2df,2p）水平的PES，揭示了KHP地层的分支比率为~ 0.65%。利用同步加速器产生的真空-紫外光电离质谱测量，通过比较C4H8O4+（KHP电离）和C4H7O2+（KHP损失ho2的离子碎片）的光电离效率谱与计算的绝热电离能和外观能，证实了EVE臭氧分解过程中KHPs （C4H8O4）的形成。
Calculations and experiments were conducted on ozonolysis of ethyl vinyl ether (EVE) and butyl vinyl ether to identify an unconventional diradical intermediate generated from the O–O bond cleavage of primary ozonide. The diradical can undergo a H atom shifting process that yields keto-hydroperoxide (KHP), the characteristic product that identifies the existence of a diradical intermediate. RRKM-ME calculation, based on the PES at the CCSD(T)/VTZ//M06-2X/6-311++G(2df,2p) level, disclosed branching ratios of ∼0.65% for KHP formation. Using synchrotron-generated vacuum-ultraviolet photoionization mass spectrometry measurements, the formation of KHPs (C4H8O4) in ozonolysis of EVE was confirmed by ion signals of C4H8O4+(ionization of KHP) and C4H7O2+(ion fragment from the loss of HO2from KHP) by comparing their photoionization efficiency spectra with the calculated adiabatic ionization energies and appearance energies.