Homolytic v Heterolytic Cleavage
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Key Questions
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Bond cleavage is the splitting of a chemical bond.
There are two types of bond cleavage: homolytic and heterolytic.
In homolytic cleavage, the two electrons in the bond are divided equally between the products.
In heterolytic cleavage, one atom gets both of the shared electrons.
Ernest Z. · 2 · 2 comments · Dec 11 2014
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Homolytic cleavage is the breaking of a covalent bond in such a way that each fragment gets one of the shared electrons.
The word homolytic comes from the Greek homoios, "equal", and lysis, "loosening".
For example, the homolytic cleavage of a Br-Br bond is
Homolytic cleavage produces free radicals — atoms with unpaired valence electrons.
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Heterolytic or ionic fission is the breaking of a covalent bond in such a way that one atom gets both of the shared electrons.
The word heterolytic comes from the Greek heteros, "different", and lysis, "loosening".
Heterolytic cleavage is most likely to occur in polar bonds. And the electrons will move toward the more electronegative atom.
If both atoms are originally uncharged, the process generates a cation and an anion.
An example is the heterolytic cleavage of the C-Br bond in t-butyl bromide.
Since Br is more electronegative than C, the electrons move to the Br. We get a t-butyl cation and a bromide anion.
