悬浮中继增强H2O2选择性在二氧化减少期间通过双二基Co-N2O2复合体调解
Asa W Nichols1, Emma N Cook1, Yunqiao J Gan2
1Department of Chemistry, University of Virginia, McCormick Rd., PO Box 400319, Charlottesville, Virginia 22904-4319, United States.
Journal of the American Chemical Society
|August 12, 2021
概括
复合物通常会将二氧化物减少为过氧化. 这项研究修改了复合体,以调查影响选择性的因素,发现特定的结构变化可以改变还原产品.
科学领域:
- 协调化学 协调化学
- 电触媒溶解是一种电触媒.
- 有机合成 有机合成
背景情况:
- -N2O2复合物是用于二氧化物 (O2) 减少的常用电催化剂.
- 这些复合物通常对过氧化 (H2O2) 生产具有选择性.
- 之前的研究已经确定了一种产生水 (H2O) 的CO (III) -N2O2复合物作为主要产物,这表明了独特的机械路径.
研究的目的:
- 为了研究一种假设,即-氧化中间体上的质子化位点决定了产品的选择性.
- 合成和研究一种新的Co(III) 复合物,其悬浮的甲基 (-OMe) 组旨在影响质子化.
- 在不同的溶剂和酸性条件下阐明控制O2降解选择性的机械路径.
主要方法:
- 合成了一种新型的Co(III) 复合体,其中包括悬浮的质子捐赠组.
- 用不同强度的酸和减少剂对乙尼 (MeCN) 的电催化研究.
- 电子偏磁共振 (EPR) 谱学用于识别关键中间体,如-超氧化物种.
主要成果:
- 新的Co (III) 综合体展示了依赖酸强度和悬挂继电器的存在的双催化系统.
- 在MeCN中,悬浮中继主要促进了H2O2的产生,与以前的H2O选择性形成鲜明对比.
- EPR研究证实了Co(III) -超氧化物的形成,在悬浮的-OMe组中观察到增强的O2反应性.
结论:
- 质子捐赠者的近距离和性质显著影响了催化O2降解中的反应途径和产品选择性.
- 悬浮质子继电器可以改变从水到过氧化生产的选择性.
- 了解这些机械细节对于设计用于选择性O2转换的先进电催化剂至关重要.
相关概念视频
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
11.2K
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
11.2K
02:35Regioselectivity of Electrophilic Additions-Peroxide Effect
9.2K
In the presence of organic peroxides, the addition of hydrogen bromide to an alkene yields the isomer that is not predicted by Markovnikov’s rule. For example, the addition of hydrogen bromide to 2-methylpropene in the presence of peroxides gives 1-bromo-2-methylpropane. This addition reaction proceeds via a free radical mechanism, which reverses the regioselectivity. The free radical reaction mechanism involves three stages: initiation, propagation, and termination.
9.2K
02:04Oxidation of Alkenes: Anti Dihydroxylation with Peroxy Acids
6.3K
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.
6.3K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.6K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.6K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
19.3K
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.
19.3K
02:36Regioselectivity and Stereochemistry of Hydroboration
8.6K
A significant aspect of hydroboration–oxidation is the regio- and stereochemical outcome of the reaction.
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
Hydroboration proceeds in a concerted fashion with the attack of borane on the π bond, giving a cyclic four-centered transition state. The –BH2 group is bonded to the less substituted carbon and –H to the more substituted carbon. The concerted nature requires the simultaneous addition of –H and –BH2 across the same face of the alkene giving syn...
8.6K