Question

the best method for synthesis of given ether by Williamson’s ether synthesis is:

A.

B.

C.

D.

Answer 1

Hint: Williamson ether synthesis is a reaction which is used to prepare ethers. It uses an organohalide compound, which
is a compound that contains a halogen along with a carbon alkyl chain, which reacts with an alkoxide to yield ethers.

Complete answer:
Williamson synthesis for ethers involve a reaction sequence, where an alkoxide reacts with a alkyl halide through the mechanism of nucleophilic substitution reaction, which is a ${{S}_{N}}^{2}$ type of reaction. The alkoxide involved is usually a sodium alkoxide which is readily reduced to remove the sodium metal ion, the remaining is the alkoxide ion which is used in the reaction. The alkoxide ion replaces the nucleophile, bromine ion and forms an ether.
In the given reaction, the mechanism followed is ${{S}_{N}}^{2}$which is followed by inversion of configuration where the attacking nucleophile gets attached from the back side. So, reaction c favors this condition, as the removal of Br from the bulky group is easier also the alkoxide ion attacks from the opposite side to yield the product. While in other reactions, the alkoxide is the carbon ring, which does not get attached to the carbon chain due to its bulkiness, so the alkoxide attaching is favored.
The reaction is as follows:

Hence, option c is the correct way for ether synthesis.

Note:
The alkoxide is formed from the reaction of an alcohol with a metal ion. The metal ion is sodium preferably which is present as a base NaOH. The reaction uses the acidic nature of alcohols, and removes the hydrogen ion to form an alkoxide. This is the first step of Williamson ether synthesis.