Ozonolysis of isoprene, the most abundant alkene, produces three distinct Criegee intermediates (CIs): CH₂OO, methyl vinyl ketone oxide (MVKO) and methacrolein oxide (MACRO). The oxidation of SO₂ by CIs is a potential source of H₂SO₄, an important precursor of aerosols. Here we investigated the UV-visible spectroscopy and reaction kinetics of thermalized MACRO. An extremely fast reaction of anti-MACRO with SO₂ has been found, k_SO2 = (1.5 ± 0.4) × 10⁻¹⁰ cm³ s⁻¹ (±1σ, σ is the standard deviation of the data) at 298 K (150 − 500 Torr), which is ca. 4 times the value for syn-MVKO. However, the reaction of anti-MACRO with water vapor has been observed to be quite slow with an effective rate coefficient of (9 ± 5) × 10⁻¹⁷ cm³ s⁻¹ (±1σ) at 298 K (300 to 500 Torr), which is smaller than current literature values by 1 or 2 orders of magnitude. Our results indicate that anti-MACRO has an atmospheric lifetime (best estimate ca. 18 ms at 298 K and RH = 70%) much longer than previously thought (ca. 0.3 or 3 ms), resulting in a much higher steady-state concentration. Owing to larger reaction rate coefficient, the impact of anti-MACRO on the oxidation of atmospheric SO₂ would be substantial, even more than that of syn-MVKO.

异戊二烯（最丰富的烯烃）的臭氧分解产生三种不同的 Criegee 中间体 (CI)：CH ₂ OO、甲基乙烯基酮氧化物 (MVKO) 和甲基丙烯醛氧化物 (MACRO)。_{Cls 对 SO 2}的氧化是 H 2 SO 4 的潜在来源，H ₂ SO ₄是气溶胶的重要前体。在这里，我们研究了热化 MACRO 的紫外-可见光谱和反应动力学。已发现anti -MACRO 与 SO ₂的极快反应， k _SO2  = (1.5 ± 0.4) × 10 ^-10  cm ³  s ^-1 (±1 σ , σ是数据的标准偏差）在 298 K (150 − 500 Torr)，大约是 syn -MVKO值的 4 倍。然而，已观察到反MACRO 与水蒸气的反应相当缓慢 ， 在298 ^{K （} 300^至500 Torr)，比当前文献值小 1 或 2 个数量级。我们的结果表明，反MACRO 的大气寿命（在 298 K 和 RH = 70% 时的最佳估计约为 18 ms）比之前认为的（约 0.3 或 3 ms）长得多，从而导致更高的稳态浓度. 由于反应速率系数较大，影响anti -MACRO 对大气 SO ₂的氧化作用显着，甚至超过syn -MVKO。