Chung Chen-An, Lee Yuan-Pern
Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 300093, Hsinchu, Taiwan.
Center for Emergent Functional Matter Science, National Chiao Tung University, 300093, Hsinchu, Taiwan.
Commun Chem. 2021 Jan 22;4(1):8. doi: 10.1038/s42004-020-00447-1.
Methyl vinyl ketone oxide (MVKO) is an important Criegee intermediate in the ozonolysis of isoprene. MVKO is resonance stabilized by its allyl moiety, but no spectral characterization of this stabilization was reported to date. In this study, we photolyzed a mixture of 1,3-diiodo-but-2-ene and O to produce MVKO and characterized the syn-trans-MVKO, and tentatively syn-cis-MVKO, with transient infrared spectra recorded using a step-scan Fourier-transform spectrometer. The O‒O stretching band at 948 cm of syn-trans-MVKO is much greater than the corresponding bands of syn-CHCHOO and (CH)COO Criegee intermediates at 871 and 887 cm, respectively, confirming a stronger O‒O bond due to resonance stabilization. We observed also iodoalkenyl radical CHC(CH)I upon photolysis of the precursor to confirm the fission of the terminal allylic C‒I bond rather than the central vinylic C‒I bond of the precursor upon photolysis. At high pressure, the adduct CHC(CH)IOO was also observed. The reaction mechanism is characterized.
甲基乙烯基酮氧化物（MVKO）是异戊二烯臭氧分解过程中一种重要的克里奇中间体。MVKO通过其烯丙基部分实现共振稳定，但迄今为止尚未有关于这种稳定化的光谱表征报道。在本研究中，我们光解1,3 - 二碘 - 丁 - 2 - 烯与O的混合物以生成MVKO，并使用步进扫描傅里叶变换光谱仪记录的瞬态红外光谱对顺 - 反式 - MVKO以及初步确定的顺 - 顺式 - MVKO进行了表征。顺 - 反式 - MVKO在948 cm处的O‒O伸缩带远大于顺 - CHCHOO和(CH)COO克里奇中间体在871和887 cm处的相应谱带，这证实了由于共振稳定作用导致O‒O键更强。我们在光解前体时还观察到了碘代烯基自由基CHC(CH)I，以确认光解时前体末端烯丙基C‒I键而非中心乙烯基C‒I键的断裂。在高压下，还观察到了加合物CHC(CH)IOO。对反应机理进行了表征。
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