Homolysis (chemistry)

In the homolytic cleavage or homolytic bond cleavage and radical reaction is a covalent bond between two atoms by external influences, such as high-frequency split light (photolysis ) or heat ( thermolysis ), so it is a kind of dissociation. Here, each leaving a binding electron after cleavage of A-B in each of the previous binding partner ( A and B), there arise radical ( A * and B * ) radicals occur predominantly one when the particles enter into a reaction with low polar bonds. Very frequently they occur in the gas state, when the kinetic energy of the particles is large enough to allow cleavage at the collision.

The formation of free radicals is preferably carried out in non-polar medium, as in the polar medium, the formation of ions is often favored. Homolytic cleavage is used for the generation of free radicals, the radical as a starting an application

• In polymer chemistry,
• With halogenation of alkanes
• In the halogenation of alkenes in the allylic

An example of radical generation is the light-induced homolysis of chlorine:

In the photolysis of acetone initially arise each a methyl radical and an acetyl radical.

The reversal of the homolytic cleavage is the colligation ( recombination of two radicals with the formation of a single bond ).

Dissociation energies

Dissociation energies are considered to be a measure of the stability of covalent bonds. You specify the amount of energy needed to cleave a bond homolytically. Therefore, this value is greater than single bonds at multiple bonds.