Free Radical, Examples, Types, and stability of Free radicals

Table of Contents

Free radical is defined as any atom or group of atoms that contain unpaired or odd electrons. In other words, free radicals are atoms or groups of atoms with unpaired electrons in outer shell configuration. When a neutral molecule undergoes homolytic fission, each of the bonded atoms retains one electron from the shared pair, and hence free radicals are produced.

structure of free radical
structure of free radical

Some of the features of free radicals are:

  • sp2 hybridization
  • Geometry of carbon atom is planar, and have bond angles of 120o
  • Highly reactive i.e. less stable
  • Free radical shows paramagnetic behaviour due to  spin of the odd electron
  • Behave as oxidant or reductant as it has tendency to accept or donate electrons

Examples of free radicals

Some of the examples of free radicals are

example of free radical

Types of free radical

Mostly there are two types of free radicals. They are neutral free radical and Charged (cation/anion) free radical.

types of free radical

Sources of free radicals

  • Environmental pollution
  • Radiations
  • Ozone layer
  • Mitochondria
  • Peroxisomes

Free radical formation

Some of the major ways of generation of free radicals include:

Homolytic cleavage:

homolytic fission

Photocatalytic cleavage:

photocatalytic cleavage, free radical

Abstraction of atom:

free radical. abstraction of photon

Free radical stability:

Free radical stability order: Methyl free radical < primary free radical < secondary free radical < tertiary free radical

stability of free radical

Stability of free radical

  • Greater the number of hyperconjugating structures of species, greater is the stability of free radical. Thus the increasing order of stability of free radical is 1o < 2o < 3o free radical
  • Stability of free radical increases by the resonance effect

FAQs

What are free radicals?

Free radicals are any atom or group of atoms that contain unpaired or odd electrons.

Free radical polymerization

Free radical polymerization is the process of formation of the polymer by the addition of free radicals unit or block.

free radical bromination

The photochemical reaction in which bromine is substituted for Hydrogen on an alkane is called free radical halogenation.

free radical halogenation

The photochemical reaction in which chlorine or bromine is substituted for Hydrogen on an alkane is called free radical halogenation.

free radical scavenger

Those substances that help in the protection of cells from being damaged by free radicals are called free radical scavengers.

What causes free radicals?

The cleavage like homolytic cleavage, photolytic cleavage, abstraction of an atom of species, etc. causes free radical formation.

Is O3 a free radical?

No, O3 is not a free radical.

Which free radical would be most stable?

Depending on the number of carbon groups attached to the carbon atom containing unpaired electrons, tertiary free radical is the most stable.

Free radical

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