功能化和动力稳定 [4] 环旋系统及其极度曲的烯环的芳香性
Takashi Tsuji1, Masahiro Okuyama, Masakazu Ohkita
1Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan. tsuji@sci.hokudai.ac.jp
Journal of the American Chemical Society
|January 23, 2003
概括
固态阻碍的替代剂动态稳定 [4] cyclophanes,使得研究他们的属性. 即使在严重曲的情况下,环的芳香度也保持不变,NMR和计算分析证实了这一点.
科学领域:
- 有机化学 有机化学
- 超分子化学 超分子化学
- 摄影化学的使用.
背景情况:
- [4]帕拉cyclophanes是压力循环分子,在材料科学中具有潜在的应用.
- 它们的合成和稳定性往往受到反应性桥头部位的限制.
- 了解压力芳香系统的电子特性对于设计新分子至关重要.
研究的目的:
- 为了动态稳定 [4] 帕拉西克洛芬骨架使用硬质阻碍替代剂.
- 为了研究这些稳定 [4] paracyclophanes 的特性和功能.
- 探索环旋中严重曲的二烯部分的芳香度和稳定性.
主要方法:
- 合成具有固体要求高的功能组的1,4桥型德华二.
- 在矩阵隔离 (77 K) 下对Dewar烯前体进行光化学芳香化.
- 使用电子吸收光谱,NMR光谱和计算方法 (GIAO,HF-DFT) 的表征.
主要成果:
- 形成动力稳定 [4] cyclophanes与不同的半衰期取决于替代剂.
- 成功测量了1H NMR频谱的衍生体24,表明显著的二氧化性.
- 计算分析证实,在严重曲的环中保留了芳香度,并得到了磁性标准的支持.
- 旋风24在能量方面受到压力,恢复到其Dewar烯前体,其半衰期在-20°C下为15±5分钟.
结论:
- 固体阻碍有效地稳定了 [4] cyclophanes,允许它们的隔离和表征.
- 这些环氧醇中严重曲的烯环保留了显著的芳香特性.
- 这项研究提供了关于分子应变,芳香度和旋化学中的动力稳定性之间的关系的见解.
相关概念视频
Cycloalkanes
Cycloalkanes are saturated cyclic hydrocarbons with carbon atoms arranged in the form of rings. They have two fewer hydrogen atoms than the corresponding acyclic alkane; therefore, their general formula is CnH2n. The structural formulas of cycloalkanes are simplified using the line-angle representation. The regular polygons are used to represent the cycloalkane rings, with each side representing a carbon-carbon bond.
The IUPAC nomenclature of cycloalkanes follows similar rules that apply to...
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Chair Conformation of Cyclohexane
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
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Stability of Substituted Cyclohexanes
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
Combustion Energy: A Measure of Stability in Alkanes and Cycloalkanes
The low reactivity in alkanes can be attributed to the non-polar nature of C–C and C–H σ bonds. Alkanes, therefore, were initially termed as “paraffins,” derived from the Latin words: parum, meaning “too little,” and affinis, meaning “affinity.”
Alkanes undergo combustion in the presence of excess oxygen and high-temperature conditions to give carbon dioxide and water. A combustion reaction is the energy source in natural gas, liquified petroleum gas (LPG), fuel oil, gasoline, diesel fuel, and...
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Frost Circles for Different Conjugated Systems
The inscribed polygon method is consistent with Hückel’s 4n + 2 rule and helps to learn whether the given cyclic compound is aromatic or not. The compound is stable and aromatic if every bonding molecular orbital (MO) is completely filled with a pair of electrons. However, if the non-bonding or antibonding orbitals are filled with electrons, the compound is unstable and not aromatic. Consider the Frost circle diagrams for cycloalkenes containing 4 to 8 carbons.
One-Degree-of-Freedom System
In mechanical engineering, one-degree-of-freedom systems form the basis of a wide range of electrical and mechanical components. Using these models, engineers can predict the behavior of various parts in a larger system, which gives them insight into how different forces interact with each other.
A one-degree-of-freedom system is defined by an independent variable that determines its state and behavior. One example of a one-degree-of-freedom system is a simple harmonic oscillator, such as a...
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