Using real-time mass spectrometric (MS) monitoring, we demonstrate one-step, catalyst-free spontaneous oxidation of various alcohols (ROH) to key reactive intermediates for the formation of ROO^– compounds on the surface of water microdroplets surrounded by alcohol vapor, carried out under ambient conditions. These organic peroxides (POs) can act as important secondary organic aerosols (SOA). We used hydrogen–deuterium exchange by spraying D₂O instead of H₂O to learn about the reaction mechanism, and the results demonstrate the crucial role of the water–air interface in microdroplet chemistry. We find that the formation of POs relies on electron transfer occurring at the microdroplet interface, which generates hydrogen atoms and hydroxyl radicals that lead to a cascade of radical reactions. This electron transfer is believed to be driven by two factors: (1) the emergence of a strong electrostatic potential on the microdroplet’s surface; and (2) the partial solvation of ions at the interface. Mass spectra reveal that the formation of POs is dependent on the alcohol structure, with tertiary alcohols showing a higher tendency to form organic peroxides than secondary alcohols, which in turn are more reactive than primary alcohols.

中文翻译：

---

醇蒸气包围的水微滴导致醇自发氧化成有机过氧化物


利用实时质谱 (MS) 监测，我们演示了各种醇 (ROH) 一步、无催化剂自发氧化为关键反应中间体，从而在水表面形成 ROO ^– 化合物被酒精蒸气包围的微滴，在环境条件下进行。这些有机过氧化物（PO）可以作为重要的二次有机气溶胶（SOA）。我们通过喷射 D ₂ O 代替 H ₂ O 进行氢-氘交换来了解反应机理，结果证明了水-空气界面在微滴中的关键作用化学。我们发现 PO 的形成依赖于微滴界面处发生的电子转移，从而产生氢原子和羟基自由基，从而导致一系列自由基反应。这种电子转移被认为是由两个因素驱动的：（1）微滴表面出现强静电势； (2)界面处离子的部分溶剂化。质谱显示，PO 的形成取决于醇结构，叔醇比仲醇更容易形成有机过氧化物，而仲醇又比伯醇更具反应性。