Question

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Synthesis of ethyl phenyl ether may be achieved by Williamson synthesis.
Reason (R): Reaction of bromobenzene with sodium ethoxide yields ethyl phenyl ether.
In the light of the above statements, choose the most appropriate answer from the options given below :

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is NOT the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

For Williamson synthesis of mixed ethers (especially those with an aryl group), always choose the phenoxide as the nucleophile and the alkyl halide as the electrophile. Never use an aryl halide as the electrophile in a Williamson synthesis.

Answer 1

The Correct Option is C

To solve this problem, let's first understand the concepts of Williamson synthesis and analyze the given statements.

Assertion (A): Synthesis of ethyl phenyl ether may be achieved by Williamson synthesis.

The Williamson synthesis is a reaction used to produce ethers. It involves the reaction of an alkoxide ion with a primary alkyl halide via an S_N2 mechanism. Thus, it is possible to synthesize ethyl phenyl ether (C₆H₅OC₂H₅) using ethoxide ions and an appropriate halide. Given the reaction is an S_N2 type, it works efficiently with primary alkyl halides.

Reason (R): Reaction of bromobenzene with sodium ethoxide yields ethyl phenyl ether.

The reaction between bromobenzene (C₆H₅Br) and sodium ethoxide (C₂H₅ONa) does not proceed via an S_N2 mechanism because the carbon atom in bromobenzene is sp² hybridized, which makes nucleophilic aromatic substitution difficult. Bromobenzene is not suitable for Williamson synthesis because the phenyl group does not undergo the S_N2 reaction. Therefore, ethyl phenyl ether cannot be formed by this method.

Now, let's evaluate the options:

• Both (A) and (R) are correct and (R) is the correct explanation of (A): This is incorrect because statement (R) is false.
• Both (A) and (R) are correct but (R) is NOT the correct explanation of (A): This is incorrect because (R) is false.
• (A) is correct but (R) is not correct: This is the correct option, as explained above, because ethyl phenyl ether can be synthesized via Williamson synthesis but not through the reaction given in (R).
• (A) is not correct but (R) is correct: This is incorrect because (A) is correct.

Hence, the correct answer is: (A) is correct but (R) is not correct.