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Radical Formation: Addition

Radical Formation: Addition

Radicals can be formed by adding a radical to a spin-paired molecule. This is typically observed with unsaturated species, where the addition of a radical across the π bond leads to the production of a new radical by dissolving the π bond. For example, the addition of a Br radical to an alkene yields a carbon-centered radical.
Similar to charge conservation in chemical reactions, spin conservation is implicit for radical reactions. Accordingly, the product formed must possess an...

Radicals: Electronic Structure and Geometry

Radicals: Electronic Structure and Geometry

This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...

Radical Reactivity: Overview

Radical Reactivity: Overview

Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...

Radical Reactivity: Steric Effects

Radical Reactivity: Steric Effects

The presence of electron-donating, electron-withdrawing, or conjugating groups adjacent to a radical center, imparts electronic stabilization to the radicals. Examples of such electronically-stabilized radicals are triphenylmethyl, tetramethylpiperidine‐N‐oxide, and 2,2‐diphenyl‐1‐picrylhydrazyl. These radicals are remarkably stable and are known as persistent radicals. Some of the persistent radicals can even be isolated and purified.
Along with electronic...

¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR

¹H NMR of Conformationally Flexible Molecules: Variable-Temperature NMR

The axial and equatorial protons in cyclohexane can be distinguished by performing a variable-temperature NMR experiment. In this process, except for one proton, the remaining eleven protons are replaced by deuterium. The deuterium substitution avoids the possible peak splitting caused by the spin-spin coupling between the adjacent protons. The remaining proton flips between the axial and equatorial positions.

π Molecular Orbitals of the Allyl Radical

π Molecular Orbitals of the Allyl Radical

Allyl radicals are three-carbon conjugated systems. They are readily formed as intermediates in halogenation reactions of alkenes involving the addition of halogen to the allylic carbon instead of the double bond. As seen in allyl cations and anions, each of the three sp2-hybridized carbon atoms in allyl radicals has an unhybridized p orbital. These orbitals combine to give three π molecular orbitals.
The allyl systems have identical molecular orbitals but differ in the number of π electrons....

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Updated: Jan 18, 2026

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

形状变量 [7] 氨基基激素氨基激素

Guantao Yang¹, Lingfang Chen^2,3, Zhizhe Liu¹

¹Beijing National Laboratory For Molecular Sciences, Centre For the Soft Matter Science and Engineering, College of Chemistry, the Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, Peking University, Beijing, P. R. China.

Chemistry (Weinheim an der Bergstrasse, Germany)

|January 16, 2026

概括

此摘要是机器生成的。

研究人员合成了新的化 [7]annulenyl基. 分子结构显著影响基的稳定性和旋转分布,平面结构和特定的替代物增强持久性.

关键词:

七面体嵌入的根基.有机根源的有机根源.稳定的稳定性稳定的稳定性

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Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

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Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization

Published on: August 6, 2018

相关实验视频

Last Updated: Jan 18, 2026

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Preparation of a Corannulene-functionalized Hexahelicene by CopperI-catalyzed Alkyne-azide Cycloaddition of Nonplanar Polyaromatic Units

Published on: September 18, 2016

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Isolating Free Carbenes, their Mixed Dimers and Organic Radicals

Published on: April 19, 2019

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization

Measurement of Ultrafast Vibrational Coherences in Polyatomic Radical Cations with Strong-Field Adiabatic Ionization

Published on: August 6, 2018

科学领域:

有机化学有机化学
材料科学材料科学材料科学
物理化学物理化学

背景情况:

由于其独特的电子和结构性质,溶 [7] 氨基基基具有兴趣.
了解分子结构和基结稳定性之间的关系对于设计新材料至关重要.

研究的目的:

合成和研究一系列与子融合的 [7]annulenyl基衍生物.
为了阐明分子结构的变化如何影响旋转分布和根基持久性.

主要方法:

新型化 [7] 烯基基衍生物的合成.
电子偏磁共振 (EPR) 谱学用于分析旋转分布.
计算化学方法来支持实验发现.

主要成果:

一个平面的dibenzo[a,d][7]annulenyl骨架与非定位的旋转被确定为非替代的激素.
根基的持久性因替代剂而异;用三烯替代的根基的半衰期为23小时.
在C10的替代物改善了稳定性,但引起了轻微的曲,而trib[a,c,e][7]annulenyl基因由于非平面形状而显示较低的稳定性.
在C9上附加一个安烯基组诱导了对安烯基单元的形状变化和旋转转移.

结论:

分子结构,特别是平面性和硬质障碍,极大地影响了子融合 [7] 烯基基的稳定性和自旋特性.
战略替代可以增强激素的持久性,但非平面形状可以显著降低稳定性并改变旋转定位.
形态灵活性和替代效应提供了调整这些根基系统属性的途径.