Understanding Oxidation Reactions of Complex Organic and Biological Materials

虽然钻石被认为是“永恒的”，但所有的有机和生物材料都会随着时间的推移而降解。在氧气环境中，任何碳基材料都会经历缓慢的热力学转化为二氧化碳的过程。然而，当自由基被引入系统中时，一种名为自氧化的自蔓延连锁反应会迅速加速氧气进入材料。这种氧化过程和随后的反应的可观察到的影响是众所周知的：塑料变黄、油变酸、烤面包、脆性橡胶和漂白的颜色，仅举几例。*我们的研究目标是提高对生物和有机系统中氧化反应的理解。虽然这一领域的研究已经活跃了几十年，但这里提出的想法表明，需要更多的基础科学研究来理解并最终改变氧化化学的方向。特别是，正在开发一种高通量吸氧设备，以加速这一研究领域的发现。这个装置将被用来在几天内并行研究数百个氧化样品，而不需要添加氧化剂来加速降解过程。通过这些数据，我们希望证明一种未知的机制，导致抗氧化剂作为自由基引发剂的行为。我们还提出了一种防止这种未被识别的自由基引发反应的方法。有了这些机制，我们可以更准确地回答为什么一瓶开着的葡萄酒，充满了抗氧化剂，氧化得这么快。或者为什么丁基羟基甲苯(BHT)被广泛用作食品添加剂，而更好的抗氧化剂，如维生素E却无效，甚至对长期储存不利。*此外，还有一种相当雄心勃勃的创新技术--熔化反应陷阱(Melt-Reaction-Trap)。最终，这项技术将产生亚毫秒时间分辨率的“光谱电影”，可以使用精确的光谱工具，如拉曼光谱或红外光谱来研究，以识别反应中间产物。熔融反应陷阱技术将为我们研究生物和有机材料中的氧化反应提供前所未有的能力。我们也期待这项技术有朝一日成为研究多相反应机理的主要工具。

While a diamond is said to be « forever », all organic and biological materials endure degradation over time. Any carbon-based material in an oxygen environment undergoes a slow thermodynamic march towards carbon dioxide. When, however, free radicals are introduced in a system, a self-propagating chain reaction called autoxidation rapidly accelerates the incorporation of oxygen into the material. The observable effects of this oxidation process and subsequent reactions are well known: yellowing of plastics, rancidity of oils, burnt toast, brittle rubber, and bleached colours, to name a few.***Our research goals are to improve the understanding of oxidation reactions in biological and organic systems. While research in this area has been active for decades, the ideas proposed here illustrate that more basic science research is needed to understand and ultimately, redirect oxidation chemistry. In particular, a high-throughput oxygen uptake apparatus is being developed to accelerate discoveries in this field of research. This setup will be used to study hundreds of oxidizing samples in parallel over days, without the need to add oxidants to accelerated the degradation process. With this data, we hope to demonstrate an unrecognized mechanism that cause antioxidants to behave as radical initiators. We also propose a method to prevent this unrecognized radical initiation reaction. With these mechanisms, we can answer more precisely why an open bottle of wine, full of antioxidants, oxidizes so quickly. Or why butylated hydroxytoluene (BHT) is widely used as a food additive while a "better" antioxidant such as vitamin E is ineffective and even detrimental for long-term storage.***Additionally, a rather ambitious and innovative technique called “Melt-React-Trap” is proposed. Ultimately, this technique will yield a "spectroscopic movie" with sub-millisecond time-resolution that can be studied using precise spectroscopic tools such as Raman or infrared spectroscopy to identify reaction intermediates. The Melt-React-Trap technique will give us an unprecedented ability to study oxidation reactions in biological and organic materials. We also expect this technique to, some day, become a major tool in to study heterogeneous reaction mechanisms.**