91Ó°ÊÓ

${\mathbf{S}}_{\mathbf{N}}\mathbf{1}$ reactions lead to a combination of products when an isomer reacts with a particular reagent. One product possesses stereochemistry similar to the starting material, whereas the other product has different stereochemistry.

${\mathbf{S}}_{\mathbf{N}}\mathbf{2}$ reactions where the R isomer is the starting material, the resulting product will be an S isomer. Reactions that start with an S isomer generate an R isomer as the product.

a .The treatment of the given reactant with HBr gives rise to a racemic mixture as the product. The given alcohol is secondary, and the reaction proceeds via ${\mathrm{S}}_{\mathrm{N}}2$reaction. The reaction product with the stereochemistry can be given as:

Reaction of the corresponding alcohol with HBr

b. The treatment of the given reactant with HCl and localid="1648640045861" ${\mathrm{ZnCl}}_2$ gives the corresponding product. The reaction occurs via the${\mathrm{S}}_{\mathrm{N}}2$mechanism, and an inversion of configuration is obtained in the final product. The reaction can be given as:

c. The treatment of the given alcohol with thionyl chloride and pyridine gives rise to the product with S configuration. The reaction can be given as:

Reaction of the corresponding alcohol withlocalid="1648640051538" ${\mathrm{SOCl}}_2$ and pyridine

d The treatment of the given alcohol with TsCl and pyridine gives rise to an alkyl tosylate. The resulting alkyl tosylate reacts with KI to form a product with an S configuration. The reaction can be given as:

Reaction of the corresponding alcohol with TsCl and pyridine