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 O₂ 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⁻¹ of syn-trans-MVKO is much greater than the corresponding bands of syn-CH₃CHOO and (CH₃)₂COO Criegee intermediates at 871 and 887 cm⁻¹, respectively, confirming a stronger O‒O bond due to resonance stabilization. We observed also iodoalkenyl radical C₂H₃C(CH₃)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 C₂H₃C(CH₃)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中的重要 Criegee 中间体。MVKO 由其烯丙基部分共振稳定，但迄今为止没有报道这种稳定性的光谱表征。在这项研究中，我们光解了 1,3-二碘-丁-2-烯和 O ₂的混合物以产生 MVKO 并表征了顺-反式-MVKO 和暂定的顺-顺式-MVKO，使用瞬态红外光谱记录步进扫描傅里叶变换光谱仪。syn - trans -MVKO 在 948 cm ^-1处的 O-O 伸缩带远大于syn -CH _{3的相应带}CHOO 和 (CH ₃ ) ₂ COO Criegee 中间体分别位于 871 和 887 cm ^-1处，证实了由于共振稳定而产生更强的 O-O 键。我们还观察到碘代烯基自由基 C ₂ H ₃ C(CH ₃ )I 在前体光解时发生裂变，以证实在光解时裂变的是末端烯丙基 C-I 键，而不是前体的中心乙烯基 C-I 键。在高压下，还观察到加合物 C ₂ H ₃ C(CH _{3 )IOO。}表征了反应机理。