通过铁三碳酸的协调稳定了质子的多少?
Martin Galvin1, J Peter Guthrie, Claire M McDonnell
1School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
Journal of the American Chemical Society
|December 20, 2008
概括
铁三碳基 (Fe ((CO) 3) 组显著稳定了环二烯酸,使其不那么酸性,并改变了其水解速率. 这种协调会影响有机离子的稳定性和反应性.
科学领域:
- 有机金属化学 有机金属化学
- 反应动力学反应动力学
- 计算化学计算化学
背景情况:
- 有机的反应性在各种化学过程中至关重要.
- 了解金属协调对有机离子稳定性的影响是关键.
研究的目的:
- 研究Fe(CO) 3协调对循环二烯酸的水解和酸度的影响.
- 为了比较协调和不协调的环二烯离子的反应性.
主要方法:
- 循环乙烯酸水解的动力和平衡测量.
- 密度函数理论 (DFT) 计算用于能量转移估计.
主要成果:
- 铁CO) 3协调会使循环二烯酸离子的pKR从-2.1增加到4.7.
- 协调性离子体的水解有利于外异构体的形成,而不是内异构体的10^7倍.
- DFT计算估计,协调性离子体去质子化的pKa值为8.
结论:
- 铁 (Fe) 氧化碳 (CO) 3 协调能大大降低循环二烯酸的酸度 (46 kcal/mol).
- 在水解中观察到的立体选择性不是由于同位素稳定性差异.
- 金属协调提供了一个强大的策略来调节有机中间体的特性.
相关概念视频
Electrophilic Aromatic Substitution: Nitration of Benzene
The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the nitronium ion, which is linear in shape. The reaction occurs through the interaction of two strong acids, sulfuric and nitric acid.
Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene
Chlorination and bromination are important classes of electrophilic aromatic substitutions, where benzene reacts with chlorine or bromine in the presence of a Lewis acid catalyst to give halogenated substitution products. A Lewis acid such as aluminium chloride or ferric chloride catalyzes the chlorination, and ferric bromide catalyzes the bromination reactions. During the bromination of alkenes, bromine polarizes and becomes electrophilic. However, in the bromination of benzene, the bromine...
Structure of Benzene: Kekulé Model
In 1865, August Kekule suggested the structure of benzene according to the structural theory of organic chemistry based on the three assertions—formula of benzene is C6H6, all the hydrogens of benzene are equivalent, and each carbon must have four bonds due to its tetravalency.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
He proposed that benzene has a cyclic structure of six carbon atoms attached to one hydrogen atom each, with three alternating pi bonds.
Electrophilic Aromatic Substitution: Sulfonation of Benzene
Sulfonation of benzene is a reaction wherein benzene is treated with fuming sulfuric acid at room temperature to produce benzenesulfonic acid. Fuming sulfuric acid is a mixture of sulfur trioxide and concentrated sulfuric acid.
Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take place easily. For example, in the reduction of stilbene, the benzene ring remains unaffected while the alkene bond gets reduced. Hydrogenation of an alkene double bond is exothermic and a favorable process. In contrast, to hydrogenate the first unsaturated bond of benzene, an energy input is needed; that is, the process is endothermic. This is...
Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...


