Page 18 - Pharm.Org.Chem-I 02-06-05-101

Breaking of a covalent bond

a) homolytic fission

R. + Y.

Free radical formed by the effect of heat or light

b) heterolytic fission R+ + Y-

+ − Carbocation
RY

− + R- + MgX+
R MgX
Carbanion

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Reaction intermediates

Carbocations C+ Carbanions C-

Electron defficient center Electron rich center

Stabilized by EDG Stabilized by EwG

Stabilized by +I and Stabilized by –I and
resonance resonance

Called electrophile E+ Called nucleophile Nu-

React with Nu- React with E+

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