化环形复合物中的蓝色转移结与乙-d(6) 和氧化-d(4) 的复合物
Sofie N Delanoye1, Wouter A Herrebout, Benjamin J van der Veken
1Department of Chemistry, Universitair Centrum Antwerpen, Groenenborgerlaan 171, B-2020 Antwerp, Belgium.
Journal of the American Chemical Society
|October 3, 2002
概括
这项研究揭示了光环形体在液体中与氧化-d4和-d6形成键复合体. 复杂化导致光环形C-H延伸的蓝色转移,随着化程度的变化而变化.
科学领域:
- 物理化学 物理化学
- 频谱学是一种光谱学.
- 计算化学计算化学
背景情况:
- Haloforms (HCClnF3-n) 是一种具有不同C-H键强度的化甲衍生物.
- 键在分子相互作用和复杂的形成中起着至关重要的作用.
- 之前的研究已经探讨了环状相互作用,但冷溶剂中的详细光谱分析是有限的.
研究的目的:
- 研究形和含氧基 (氧化-d4,乙-d6) 之间的 1:1 复合物的形成和特性.
- 用红外光谱学分析复合后的结构和电子变化.
- 用理论上的初始计算来证实实验发现.
主要方法:
- 红外 (IR) 光谱学被用来研究形 (n=0-3) 与氧化-d4 和-d6 在冷温度下液态中混合的混合物.
- 分析的重点是自由和复杂环状单体的C-H拉伸频率和IR强度.
- 使用CP校正的梯度技术进行了ab initio计算,以支持实验观测.
主要成果:
- 观察到1:1复合物的形成,其特点是形C-H键与基的氧原子之间的键.
- 检测到光环形C-H拉伸频率的蓝色转移,转移的幅度从 (CHCl3) 增加到 (CHF3).
- 复合与自由的C-H伸展带的IR强度的比率显著下降,从合金复合物的50以上降至合金复合物的0.1左右.
结论:
- 这项研究证实了液态基矩阵中形体和氧化基之间的结复合体的形成.
- 观察到的光谱变化,包括蓝色转移和强度变化,与键的强度一致,它从CHCl3增强到CHF3.
- 理论计算成功地重现了实验趋势,验证了拟议的相互作用模型,并提供了对复合体电子结构的更深入的了解.
相关概念视频
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.
Preparation of Epoxides
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
The Cope rearrangement is classified as a [3,3] sigmatropic shift in 1,5-dienes, leading to a more stable, isomeric 1,5-diene. The reaction involves a concerted movement of six electrons, four from two π bonds and two from a σ bond, via an energetically favorable chair-like transition state.


