chemistry class 12 project

1. WELCOME

2. P. By:-Santosh
Pradhan Class:-XII
G. By:-Dr. D.K.Mishra
Sir
Chemistry
Project

3. Mechanism of Nucleophilic
Substitution
1. SN2 Reaction
2. SN1 Reaction

4. 1. SN2 Reactions :--
• SN2 is a kind of nucleophilic substitution reaction
mechanism, the name referring to the Hughes-
Ingold symbol of the mechanism.
• Since two reacting species are involved in the slow
(rate-determining) step, this leads to the term
substitution nucleophilic (bi-molecular) or SN2.

5. RX + NU RNU
.. ..

6. Steps of SN2 Reaction :-
1. The carbon - nucleophile bond
forms and carbon-leaving group
breaks simultaneously through a
transition state.
2. Now,the leaving group is pushed
out of the transition state on the
opposite side of the Carbon-
nucleophile bond, forming the

8. Nucleophile approches towards
reactant:-
(Nucleophi
le)
(Reactant)

9. Simultaneously attacking of
nucleophile and releasing of
halogen atom:-
(Transition state)

10. Halogen released and
nucleophile attached

11. 2. SN1 Reaction:-
• The SN1 reaction is a nucleophilic
substitution reaction where the rate-
determining step is unimolecular.
• This reaction involves the formation of a
carbocation intermediate.
• The SN1 reaction is often referred to as
the dissociative mechanism in inorganic
chemistry.

13. SN1 Reaction Mechanism:-
Step 1:-
The carbon-bromine bond is a
polar covalent bond. The cleavage
of this bond allows the removal of
the leaving group (bromide ion).
When the bromide ion leaves the
tertiary butyl bromide, a
carbocation intermediate is
formed.

14. •Step 2:-
In the second step of the SN1
reaction mechanism, the
carbocation is attacked by the
nucleophile.
Since water is used as a solvent,
an oxonium ion intermediate is
formed.

15. Step 3:-
The positive charge on the
carbocation was shifted to the
oxygen in the previous step.
The water solvent now acts as a
base and deprotonates the
oxonium ion to yield the required
alcohol along with a hydronium
ion as the product.

17. Removal of leaving group and formation of
Carbocation intermediate:-
(Carbocation
intermediate)

18. Attacking of nucleophile and
formation of oxonium ion
intermediate:-
(Oxonium ion)

19. Deprotonation of oxonium ion
and formation of required
alcohol:-
(Tertiary alcohol)