在与结合的醇的氧化过程中协同的质子电子转移
Ian J Rhile1, Todd F Markle, Hirotaka Nagao
1Department of Chemistry, Campus Box 351700, University of Washington, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|May 4, 2006
概括
研究了涉及和悬浮的质子合电子转移 (PCET) 反应. 这些反应通过协同的质子电子转移 (CPET) 发生,而不是逐步的机制,具有显著的重组能量.
科学领域:
- 物理化学 物理化学
- 电化学 电化学 电化学
- 化学动力学 化学动力学
背景情况:
- 具有悬挂基 (HOAr-B) 的类是研究质子合电子转移 (PCET) 的模型系统.
- 了解PCET的机制对于各种化学和生物过程至关重要.
研究的目的:
- 为了研究三种具有悬挂基 (初级氨基,伊米达,皮里丁) 的醇在乙二中的氧化机制.
- 确定氧化还原潜力和反应途径,特别区分协同质子电子转移 (CPET) 和阶段性机制.
- 用电化学和化学方法分析这些PCET反应的动力学和热力学.
主要方法:
- 使用各种单电子氧化剂进行化学氧化.
- 几乎可逆的电化学氧化.
- 热化学论证的分析,动态同位素效应,以及马库斯理论用于机械阐明.
主要成果:
- 氧化产物是基基与质子转移到基, (*)OAr-BH(+),表明一个PCET过程.
- 由于推动质子转移的驱动力,还氧化潜力降低.
- 证据强烈支持协调的质子电子转移 (CPET) 机制,排除了初始电子或质子转移.
- 在CPET中观察到大量的重组能量 (λ = 2356 kcal mol-1).
- 不同质电子转移的速率常数与亚亚巴特马库斯理论的预测一致.
结论:
- 具有悬挂基的醇的氧化通过CPET机制进行.
- 观察到的动力学和热力学与阿迪亚巴特马库斯理论相一致.
- 这些发现为CPET反应提供了详细的见解,其中质子和电子转移发生在不同的地点.
相关概念视频
Oxidation of Alkenes: Syn Dihydroxylation with Potassium Permanganate
Alkenes can be dihydroxylated using potassium permanganate. The method encompasses the reaction of an alkene with a cold, dilute solution of potassium permanganate under basic conditions to form a cis-diol along with a brown precipitate of manganese dioxide.
Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
Diols are compounds with two hydroxyl groups. In addition to syn dihydroxylation, diols can also be synthesized through the process of anti dihydroxylation. The process involves treating an alkene with a peroxycarboxylic acid to form an epoxide. Epoxides are highly strained three-membered rings with oxygen and two carbons occupying the corners of an equilateral triangle. This step is followed by ring-opening of the epoxide in the presence of an aqueous acid to give a trans diol.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Oxidation of Phenols to Quinones
In the presence of oxidizing agents, phenols are oxidized to quinones. Quinones can be easily reduced back to phenols using mild reducing agents. The electron-donating hydroxyl group enhances the reactivity of the aromatic ring, enabling oxidation of the ring even in the absence of an α hydrogen.
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
o-hydroxy phenols are oxidized to o-quinones and p-hydroxy phenols to p-quinones. Such redox reactions involve the transfer of two electrons and two protons. The reversible redox property is crucial in...
Phase I Reactions: Oxidation of Aliphatic and Aromatic Carbon-Containing Systems
Phase I biotransformation reactions are integral to drug metabolism, predominantly involving oxidative, reductive, and hydrolytic transformations. Chief among these are oxidative reactions, which enhance the hydrophilicity of xenobiotics and introduce polar functional groups to facilitate their elimination from the body.
Oxidation reactions are fundamental in aromatic carbon-containing systems. An example is the hydroxylation of phenobarbital, a process that transforms it into...
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Phase I Reactions: Oxidation of Carbon-Heteroatom and Miscellaneous Systems
Oxidative reactions are pivotal in metabolizing numerous compounds, including pharmaceutical drugs. These reactions often occur in carbon-heteroatom systems, such as carbon-nitrogen, carbon-sulfur, and carbon-oxygen.
In carbon-nitrogen systems, aliphatic and aromatic amines can undergo oxidative reactions. Secondary and tertiary amines, like those found in tricyclic antidepressants, can undergo N-dealkylation, a process that involves the oxidation of the alkyl group. In addition, oxidative...
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