Utente:Grasso Luigi/sanbox1/Omolisi (chimica)

In chimica, omolisi (dal Greco ὅμοιος, homoios, "uguale," e λύσις, lusis, "perdita") o fissione omolitica indica la dissociazione di un legame chimico presente in una molecola da un processo in cui ciascuno dei frammenti conserva uno della coppia elettroni nel legame di partenza. During homolytic fission of a neutral molecule with an even number of electrons, two free radicals will be generated. That is, the two electrons involved in the original bond are distributed between the two fragment species. The energy involved in this process is called bond dissociation energy. Bond cleavage is also possible by a process called heterolysis.

Because the relatively high energy required to break bonds in this manner, homolysis only occurs under certain circumstances:

• Ultraviolet radiation (e.g. sunlight causing sunburns)
• Heat
  • Certain intramolecular bonds, such as the O–O bond of a peroxide, are weak enough to spontaneously homolytically dissociate with a small amount of heat.
  • High temperatures in the absence of oxygen (pyrolysis) can induce homolytic elimination of carbon compounds.

Voci correlate

• Alpha cleavage