Chapter 12, Problem 12.20P

Interpretation Introduction

Interpretation:

The missing compounds for the given reaction sequence from D to F are to be identified.

Concept introduction:

Alkyl halides, when heated with a strong base, undergo E2 elimination reactions to yield the most substituted alkene as the major product. Heat favors elimination over substitution. The leaving group and the hydrogen on the adjacent carbon must have the anticoplanar geometry. If such geometry is absent in the reactant molecule, then the carbon-carbon single bond is rotated as required to get the leaving group and the adjacent hydrogen anticoplanar to each other.

The alkene that has been formed as a result of the above reaction is converted into an epoxide using peroxyacid. The stereochemistry of the alkene is retained in the epoxide formed.

Epoxides undergo ${\text{S}}_{\text{N}}\text{2}$ type of reactions with strong nucleophiles such as alkyl magnesium halides (known as Grignard reagent) to yield a substitution product. As the reaction is ${\text{S}}_{\text{N}}\text{2}$, inversion of the configuration is observed in the substituted product. If chiral products are produced, then a mixture of stereoisomers is produced as a final product.