1. β-eIimination:
Elimination reactions involve the cleavage of a a bond and tórmation of air bond. A nucleophilic pair of electrons heads into a new it bond as a leaving group departs. This process is called 3-elimination because the bond Í to the nucleophilic pair of electrons breaks.
Example:
(a) n-propyl bromide on reaction with alcoholic KOH give propene. in this reaction hydrogen and Br are eliminated.
(b) Acid-catalysed dehydration of alcohols
2. Electrophilic substitution:
Substitution reactions when are brought about by electrophiles are called electrophilic substitution reaction.
Example:
(a) Nitration of benzene
(b) Bromination of benzene:
