Oxidation of Secondary Hydroperoxides via αC-H Abstraction to Form Ketones and Hydroxyl Radicals: Fluorene Autoxidation as a Model System

IF 1.1 4区化学 Q3 CHEMISTRY, MULTIDISCIPLINARY

Canadian Journal of Chemistry Pub Date : 2023-07-26 DOI:10.1139/cjc-2022-0089

Mélanie Sollin, S. Hosseininasab, J. Malenfant, Mohamed EL-akhrass, Amaia Lopez de Arbina, Alicia Montulet, M. Frenette

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Abstract

Organic and biological molecules with relatively weak C-H bonds can react with O2 via a free-radical reaction called autoxidation. The primary products of these peroxyl-radical-driven reactions are hydroperoxides, R2CHOOH. If autoxidation continues, the secondary oxidation of hydroperoxides is known to form ketones, R2C=O, but this mechanism is not well characterized. Importantly, we find that ketone formation produces a highly reactive hydroxyl radical, HO•. We can trap HO• using benzene as a solvent to form quantifiable amounts of phenol. Fluorene was chosen as a model system to study this secondary oxidation in great detail. Kinetic modeling allowed the measurement of rate constants for the primary and secondary autoxidation reactions as 11.3 M-1s-1 and 25 M-1s-1, respectively. DFT modeling likewise predicts a faster oxidation for the secondary autoxidation. This type of kinetic measurement and modeling approach could be useful to study the autoxidation of plastics, petrochemicals, and lipids.

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二级氢过氧化物通过αC-H萃取生成酮和羟基自由基的氧化:芴自氧化为模型体系

C-H键相对较弱的有机和生物分子可以通过自由基反应与O2发生自氧化反应。这些过氧自由基驱动的反应的主要产物是氢过氧化物R2CHOOH。如果自氧化继续进行，已知氢过氧化物的二次氧化形成酮，R2C=O，但这一机制尚未得到很好的表征。重要的是，我们发现酮的形成产生一个高活性的羟基自由基，HO•。我们可以用苯作为溶剂捕获HO•，形成可量化的苯酚。选择芴作为模型体系，详细研究了这种二次氧化。通过动力学建模，测定了一次和二次自氧化反应的速率常数分别为11.3 M-1s-1和25 M-1s-1。DFT模型同样预测了二次自氧化的更快氧化。这种类型的动力学测量和建模方法可用于研究塑料，石油化工和脂类的自氧化。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Canadian Journal of Chemistry 化学-化学综合

CiteScore

1.90

自引率

9.10%

发文量

审稿时长

1 months

期刊介绍： Published since 1929, the Canadian Journal of Chemistry reports current research findings in all branches of chemistry. It includes the traditional areas of analytical, inorganic, organic, and physical-theoretical chemistry and newer interdisciplinary areas such as materials science, spectroscopy, chemical physics, and biological, medicinal and environmental chemistry. Articles describing original research are welcomed.