通过O结合的CO激活一氧化碳,使用十甲基甘酸-酸离子对
Andreas Berkefeld1, Warren E Piers, Masood Parvez
1Department of Chemistry, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada.
Journal of the American Chemical Society
|June 8, 2012
概括
复合体 ([Cp*(2) Sc](+)) 与一氧化碳 (CO) 反应形成新型甲基和氧化物产物. 这种反应途径涉及一种不寻常的O结合的CO添加物,证明了CO激活的新方法.
科学领域:
- 有机金属化学 有机金属化学
- 化学 化学
- 催化剂是一种催化剂.
背景情况:
- 带有酸盐对抗离子的复合物是已知的易斯酸.
- 这些复合物的与CO等小分子的反应性对催化应用很有兴趣.
研究的目的:
- 为了研究离子对[Cp*(2) Sc](+) [HB(p-C(6) F(4) R) ((3) ]-) 与D(2),α-olefins和CO的反应性.
- 使用DFT计算,阐明CO激活和产品形成的机制.
主要方法:
- 离子对的合成和表征 [Cp*(2) Sc](+) [HB(p-C(6) F(4) R) ((3)) ](-).
- 用D(2),α-olefins和CO进行反应性研究.
- 密度函数理论 (DFT) 计算以建模反应路径和中间体.
主要成果:
- 复合物对D(2) 和α-olefins没有反应,表明没有化物反向转移.
- 与二氧化碳的反应产生甲基 (2-R) 和氧化物 (3-R) 产物.
- DFT的计算揭示了一种与O结合的CO添加物和一种新型的反应机制,其中涉及一种异碳烯中间体.
结论:
- 这项研究提出了前所未有的通过复合的二氧化碳激活.
- 通过异碳烯中间体确定了一种通过CO激活的新反应通道.
- 这些发现为在有机金属化学中利用CO开辟了新的途径.
相关概念视频
Loss of Carboxy Group as CO2: Decarboxylation of β-Ketoacids
Carboxylic acids, upon heating, undergo a decarboxylation reaction by releasing carbon dioxide gas. Monocarboxylic acids do not undergo decarboxylation easily. However, a silver salt of carboxylic acid reacts with bromine or iodine under high temperature to release carbon dioxide gas and forms halide with one less carbon. This reaction is called the Hunsdiecker reaction.
Cycloaddition Reactions: MO Requirements for Photochemical Activation
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
Loss of Carboxy Group as CO2: Decarboxylation of Malonic Acid Derivatives
Just like β-keto acids—which upon thermal decarboxylation form ketones—β-dicarboxylic acids undergo decarboxylation to generate monocarboxylic acids with the liberation of carbon dioxide.
¹³C NMR: ¹H–¹³C Decoupling
The probability of having two carbon-13 atoms next to each other is negligible because of the low natural abundance of carbon-13. Consequently, peak splitting due to carbon-carbon spin-spin coupling is not observed in spectra. However, protons up to three sigma bonds away split the carbon signal according to the n+1 rule, resulting in complicated spectra.
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
A broadband decoupling technique is used to simplify these complex, sometimes overlapping, signals. Broadband decoupling relies on a...
Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.


