Understanding Oxidation Reactions of Complex Organic and Biological Materials

虽然钻石被认为是“永恒的”，但所有有机和生物材料都会随着时间的推移而降解。任何碳基材料在氧气环境中都会经历一个缓慢的热力学过程，向二氧化碳迈进。然而，当在系统中引入自由基时，称为自氧化的自蔓延链式反应迅速加速氧进入材料。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，油酸败，烧焦的面包，脆橡胶和漂白的颜色，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重新定向氧化化学。特别是，正在开发一种高通量摄氧装置，以加速这一研究领域的发现。这种设置将用于在几天内平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。有了这些数据，我们希望证明一种未被认识的机制，导致抗氧化剂作为自由基引发剂。我们还提出了一种方法来防止这种未被识别的自由基引发反应。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，氧化得如此之快。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则无效，甚至不利于长期储存。此外，一个相当雄心勃勃的和创新的技术称为“熔化反应陷阱”的建议。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（如拉曼或红外光谱）进行研究，以识别反应中间体。熔融反应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。我们也希望有一天，这项技术能成为研究非均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.**