Laboratoire d'Electrochimie, Chimie des Interfaces et Modélisation pour l'Energie, CNRS UMR 7575, Chimie ParisTech, 11, rue Pierre et Marie Curie, F-75231 Paris Cedex 05, France.
Phys Chem Chem Phys. 2011 Aug 28;13(32):14636-45. doi: 10.1039/c1cp21357a. Epub 2011 Jul 7.
A large number of organic compounds, such as ethers, spontaneously form unstable peroxides through a self-propagating process of autoxidation (peroxidation). Although the hazards of organic peroxides are well known, the oxidation mechanisms of peroxidizable compounds like ethers reported in the literature are vague and often based on old experiments, carried out in very different conditions (e.g. atmospheric, combustion). With the aim to (partially) fill the lack of information, in this paper we present an extensive Density Functional Theory (DFT) study of autoxidation reaction of diethyl ether (DEE), a chemical that is largely used as solvent in laboratories, and which is considered to be responsible for various accidents. The aim of the work is to investigate the most probable reaction paths involved in the autoxidation process and to identify all potential hazardous intermediates, such as peroxides. Beyond the determination of a complex oxidation mechanism for such a simple molecule, our results suggest that the two main reaction channels open in solution are the direct decomposition (β-scission) of DEE radical issued of the initiation step and the isomerization of the peroxy radical formed upon oxygen attack (DEEOO˙). A simple kinetic evaluation of these two competing reaction channels hints that radical isomerization may play an unexpectedly important role in the global DEE oxidation process. Finally industrial hazards could be related to the hydroperoxide formation and accumulation during the chain propagation step. The resulting information may contribute to the understanding of the accidental risks associated with the use of diethyl ether.
大量有机化合物，如醚类，通过自动氧化（过氧化物氧化）的自传播过程自发形成不稳定的过氧化物。尽管有机过氧化物的危害众所周知，但文献中报道的可过氧化化合物（如醚类）的氧化机制模糊不清，并且常常基于旧的实验，这些实验在非常不同的条件下进行（例如，大气、燃烧）。为了（部分）填补信息空白，本文我们采用广泛的密度泛函理论（DFT）研究了二乙醚（DEE）的自动氧化反应，二乙醚是实验室中广泛用作溶剂的化学物质，被认为是各种事故的罪魁祸首。这项工作的目的是研究自动氧化过程中涉及的最可能的反应途径，并确定所有潜在的危险中间体，如过氧化物。除了确定如此简单的分子的复杂氧化机制外，我们的结果表明，在溶液中打开的两个主要反应通道是引发步骤中产生的 DEE 自由基的直接分解（β-断裂）和氧攻击形成的过氧自由基的异构化（DEEOO˙）。对这两个竞争反应通道的简单动力学评估表明，自由基异构化可能在全球 DEE 氧化过程中发挥意想不到的重要作用。最后，工业危害可能与链传递步骤中过氧化物的形成和积累有关。所得信息可能有助于理解与使用二乙醚相关的意外风险。
