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Stability of Carbon Centered Free Radicals

Learning Objective: To study the structural features that contribute to the stability of a carbon-centered free radical in organic chemistry. 

Skill Level - Intermediate

 

Prerequisites: 

 

Chapter: Reactive Intermediates

Sub-topic: Free Radicals

 

Author's Note: The most common knowledge we must have gathered throughout organic chemistry study is that free radicals are highly reactive and unstable. What if I told you that there have been cases where free radicals have been isolated and stored at room temperature and found no degradation whatsoever, even in the presence of oxygen or air? If so, then there are structural features that encourage free radical stability so that it can be cornered and trapped to be studied elaborately. This section covers some of the most important ones that stabilize a carbon-centered free radical.

Stability of Carbon Centered Free Radicals

Most radicals are reactive to atmospheric oxygen. However, certain structural features increase radical stability. 

Some radicals, covered in heavily crowded protective cage-like molecular structures, or radicals surrounded by many electronegative groups, or a combination of the two, are found to be stable above room temperatures and in oxygen's presence.

 

 

The factors that stabilize carbocations...

 

The different ways to stabilize a carbon-centered radicals are:

a) Inductive 

b) Resonance 

c) Hyperconjugative

d) Electronegativity

e) Three electron bonding

 

a) Inductive stabilization of the carbon-centered radical

The carbon-centered radical is an electron-deficient carbon atom devoid of only one electron....

 

b) Resonance stabilization of the carbon radical

The resonance or delocalization allows the single electron not to be confined....

 

c) Hyperconjugative Stability (for alkyl radicals)

The C-H bonds of the alkyls shift their electron density...

 

d) Electronegativity

Since the free radical carbon is electron-deficient, the greater the electronegativity ...

 

e) Three electron bonding 

In addition to alkyl groups, free radicals are also stabilized by the ....

 

Subscribe to learn about the structural features that contribute to the stability of a carbon-centered free radical in organic chemistry. 

 

Reactive Intermediates
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Reactive Intermediates

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