91Ó°ÊÓ

When a leaving group leaves the substrate molecule, a carbocation intermediate will be formed. Then the nucleophile attacks on the carbocation and forms the required product.

• When $3°$ carbocation is formed as an intermediate, S_N1 reaction takes place.
• When role="math" localid="1648446945935" $1°$carbocation is formed as an intermediate, S_N2 reaction takes place.

All the given reactions involve the carbocation intermediates followed by the attack of the nucleophile.

a. In this reaction, Cl^- is the leaving group. Once the chloride group leaves, a $2°$carbocation is formed as an intermediate, and then S_N1 reaction takes place.

Formation of product in reaction a

b. In this reaction, I^- is the leaving group. Once it leaves, it forms $1°$carbocation, and then CN^- nucleophile attacks it to form the respective products.

Formation of product in reaction b

c. In this reaction, I^- is the leaving group. Once it leaves, it forms $3°$carbocation, and then H₂O nucleophile attacks it to form the respective products.

Formation of product in reaction c

d. In this reaction, Cl^-is the leaving group. Once it leaves, it forms $3°$carbocation, and then CH₃CH₂OH nucleophile attacks it to form the respective products.

Formation of product in reaction d

e. In this reaction, Br^- is the leaving group. Once it leaves, it forms $2°$ carbocation, and then CH₃O^- nucleophile attacks it to form the respective products.

Formation of product in reaction e

f. In this reaction, Cl^-is the leaving group. Once it leaves, it forms $1°$carbocation, and then (CH₃)₂S nucleophile attacks it to form the respective products.

Formation of product in reaction f