酸是氧化物抗氧化作用的关键
Evan A Haidasz1, Derek Meng1, Riccardo Amorati2
1Department of Chemistry, University of Ottawa , Ottawa, Ontario K1N 6N5, Canada.
Journal of the American Chemical Society
|March 30, 2016
概括
像TEMPO这样的持续性基氧化物是阻碍氨基光稳定剂的关键. 这项研究揭示了TEMPO由基再生的替代机制,解释了其抗氧化活性.
科学领域:
- 有机化学
- 聚合物科学
- 材料科学
背景情况:
- 持久性基氧化物,如2,2,6,6-四甲-1-氧化物 (TEMPO),是阻胺光稳定剂 (HALS) 的关键成分.
- HALS添加剂可以防止各种消费和工业产品的光氧化降解.
- 已确定的HALS机制涉及氧化物,基和过氧基的催化循环.
研究的目的:
- 为 (光氧化) 降解中持久性基氧化物提供替代反应机制提供证据.
- 研究酸催化在氧化物和过氧基之间的反应中的作用.
- 通过基阐明TEMPO从其离子的再生途径.
主要方法:
- 在酸的存在下,对TEMPO和过氧基之间的反应进行动力学研究.
- 测定TEMPO的离子和基之间的反应速率常数.
- 在高温下对碳化合物自氧化的反应机制的研究.
主要成果:
- 在酸的存在下,TEMPO以控制的扩散速度与过氧基发生反应.
- 基从其氧离子中再生TEMPO的速率常数大约为1-3 × 10{\displaystyle M{\displaystyle M}-1}s{\displaystyle M}-1} .
- 这种再生途径有效地与O2竞争基,其速度受酸强度的影响.
结论:
- 在HALS中提出了酸催化活性的替代机制,涉及氧离子的形成和随后的基的减少.
- 这种机制解释了在碳化合物自氧化中观察到的TEMPO的催化基捕获抗氧化活性.
- 这些发现有助于了解基于HALS和TEMPO的抗氧化剂的有效性.
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