関連する実験動画
Updated: Mar 16, 2026

08:12
Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers
Published on: December 16, 2022
4.0K
機械的に活性化されたシス・トゥ・トランス・サイクロプロパン・イソメリゼーションの単分子観察
Junpeng Wang1, Tatiana B Kouznetsova1, Stephen L Craig1
1Department of Chemistry, Duke University , Durham, North Carolina 27708, United States.
Journal of the American Chemical Society
|August 9, 2016
まとめ
トロウエンのシス-ジェム-ディフローロcyclopropaneポリマーの機械化学的活性化は2つの力移行を示しています. これらのトランジションは,メチルベンゾアートの振る舞いとは異なり,トランス同位体への同位化を含む競合する反応を示します.
科学分野:
- ポリマー化学
- 機械化学
- 材料科学
背景:
- メカノフォアは 機械的な力に晒されると 化学的変化を起こします
- cis-gem-difluorocyclopropane (cis-gDFC) はメチルベンゾアート (MB) で行動が研究されたメカノフォアである.
研究 の 目的:
- シス-gDFCポリマーの機械化学的活性化を,単分子力スペクトロスコーピーを用いて特徴づける.
- トロウエンのシス-gDFCの行動と,以前報告されたMBの行動を比較する.
主な方法:
- シス-gDFCポリマーの機械化学反応を検知するために単分子力スペクトロスコーピーを用いた.
- 化学反応を示す明確な移行を特定するために,力対拡張曲線を分析した.
主要な成果:
- トロウエンの cis- gDFCポリマーの力対伸縮曲線には2つの明確な力移行が観察されました.
- 最初の移行は ~1300 pNで発生し,MBでの以前の観測と一致しました.
- ~1800 pNでの第二の移行は,トランス-gDFC同位体の部分的形成を示し,競合する反応経路を明らかにした.
結論:
- トロウエンの cis-gDFC の機械化学的活性化には, ~ 1300 pN の力平原で競合する反応が含まれています.
- これらの競合反応には,ディラジカロイド中間体への酸素添加と,トランス-gDFC同位体への同位体化が含まれます.
- 溶媒の作用,特にトロウエンの使用は,シス-gDFCポリマーの機械化学反応に大きな影響を与えます.
関連する概念動画
Disubstituted Cyclohexanes: cis-trans Isomerism
15.0K
Depending upon the different spatial orientation of the substituents, the disubstituted cycloalkanes exhibit two types of stereoisomers. The cis isomers have the substituents on the same side of the ring, whereas the trans isomers have the substituents on the opposite sides. These stereoisomers exhibit different physical properties and cannot be interconverted without breaking the carbon-carbon bonds.
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
In cyclohexane, the substituents can occupy different positions generating distinct isomers....
15.0K
Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.8K
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.
2.8K
Photochemical Electrocyclic Reactions: Stereochemistry
2.4K
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
2.4K
Thermal and Photochemical Electrocyclic Reactions: Overview
3.2K
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.
3.2K
¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
1.4K
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
1.4K
Stereoisomerism of Cyclic Compounds
11.7K
In this lesson, we delve into the role of ring conformation and its stability, which determines the spatial arrangement and, consequently, the molecular symmetry and stereoisomerism of cyclic compounds. 1,2-Dimethylcyclohexane is used as a case study to evaluate the possible number of stereoisomers. Here, given the multiple (n = 2) chiral centers, there are 2n = 4 possible configurations that lack a plane of symmetry, as the ring skeleton exists in a non-planar chair conformation. In addition,...
11.7K

