新的可分离基基烯及其可分离的二聚体,在溶液中保持平衡
Takashi Abe1, Ryoji Tanaka, Shintaro Ishida
1Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan.
Journal of the American Chemical Society
|November 23, 2012
概括
一种新型的dialkylsilylene被合成和分离出来. 观察到其可逆二元化为四基基烯,具有灵活的硬质散体,可隔离两种物种.
科学领域:
- 有机化学 有机化学
- 无机合成 无机合成
- 频谱学是一种光谱学.
背景情况:
- 二元化合物 (西利) 是高度反应的中间体.
- 稳定西利烯的隔离需要显著的绝缘保护.
- 丝烯的二元化成丝烯是一种常见的反应途径.
研究的目的:
- 为了合成和表征一种新型可分离的dialkylsilylene.
- 为了研究烯与相应的烯之间的二分化平衡.
- 了解硬质体在稳定这些物种中的作用.
主要方法:
- 基基烯的合成 3.
- 重结晶以获得单质西利烯3和二元性四基基烯4.
- 固态结构分析 (X射线结晶学).
- 使用NMR和UV-vis光谱仪进行溶液状态的表征.
- 烯-二烯平衡的热力学分析.
主要成果:
- 成功合成并分离了dialkylsilylene 3.成功合成并分离了dialkylsilylene 3.成功合成并分离了dialkylsilylene 3.成功合成并分离了dialkylsilylene
- 隔离了四基基基烯4,一个3的二元体,具有长Si=Si键 (2.252 Å).
- 在溶液中观察了三烯和四烯之间的可逆平衡.
- 对二元化平衡的热力学参数的量化 (ΔH = -36 ± 3 kJ mol−1, ΔS = -170 ± 15 J mol−1 K−1).
- 对两种物种的稳定性和隔离性解释的固体因素 (埋藏体积的百分比) 的分析.
结论:
- 基替代物的柔性固体质量对于烯和二烯的可逆二分化和分离至关重要.
- 这项研究提供了对控制低价值化合物的稳定性和反应性的因素的见解.
- 这些发现有助于理解-多重键形成和稳定.
相关概念视频
01:29Diels–Alder Reaction: Characteristics of Dienes
The Diels–Alder reaction brings together a diene and a dienophile to form a six-membered ring. Both components have unique characteristics that influence the rate of the reaction.
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
01:29Diels–Alder Reaction Forming Bridged Bicyclic Products: Stereochemistry
Diels–Alder reactions between cyclic dienes locked in an s-cis configuration and dienophiles yield bridged bicyclic products.
01:28Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.
02:26Preparation and Reactions of Sulfides
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
02:37Disubstituted Cyclohexanes: cis-trans Isomerism
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.
01:28Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.