2. ELIMINATION REACTIONS:
• Elimination reactions are exact reverse of addition reactions.
• Its is defined as removal of atom or group of atoms from the adjacent carbon of a
molecule and this leads to the formation of multiple bonds either double bond or
triple bond depending on how many atoms are removing.
• Elimination reactions are endothermic reactions i.e,. These reactions takes place in the
presence of heat.
Elimination reactions
Alpha elimination reactions Beta elimination reactions
6. E2 MECHANISM:
It is a bimolecular reaction.
It is a single step process.
It follows second order kkinetics.
Rate α [ substrate ] [ Nucleophile].
1o alkyl halides undergo E2 Mechanism
E.g., n-propyl bromide
7. E1 MECHANISM:
It is an unimolecular reaction.
It is a two step process.
It follows first order kkinetics.
Rate α [ substrate ].
3oalkyl halides undergo E1 Mechanism
E.g., 3o butyl bromide
10. E1cb reaction :
It is a unimolecular reaction.
It is a two step process , it forms carbanion as intermediate which is conjugate base of
starting material.
It follows second order kinetics.
Rate α [ substrate ] [ Nucleophile].
It should have a poor leaving group
Beta hydrogen is highly acidic in nature.
It follows Hoffmann rule.
General reaction: