Read the passage carefully and answer the questions.
Replacement of a hydrogen atom in a hydrocarbon by an alkoxy or carboxyl group yields a class of compounds known as ethers. Ethers are classified as symmetrical or unsymmetrical on the basis of groups attached to the oxygen atoms. Diethyl ether, a symmetrical ether, has been widely used as an inhalation anesthetic. Ethers can be prepared by acid catalyzed intermolecular dehydration of alcohols and Williamson's synthesis. Acid catalyzed dehydration of alcohols is not generally preferred as it gives a mixture of elimination and substitution products. In Williamson's synthesis, an alkyl halide is allowed to react with sodium alkoxide. Ethers containing substituted Alkyl groups may also be prepared by this method. The C-O bond in ether is weakly polar and is cleaved under drastic conditions with excess of hydrogen halides. In electrophilic substitution, the alkoxy group deactivates the aromatic ring and directs the incoming group to ortho and para positions.
Which type of ether is anisole?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Phenyl Alkyl ether
Ethers are named and classified by the two groups attached to the oxygen atom. If both are alkyl groups the ether is a dialkyl ether (\( \ce{C2H5-O-C2H5} \)); if both are aryl groups it is a diaryl ether (\( \ce{C6H5-O-C6H5} \)); if one is an aryl group and the other an alkyl group it is an alkyl aryl ether.
Anisole is methoxybenzene, \( \ce{C6H5-O-CH3} \): a phenyl group and a methyl group on the same oxygen. So anisole is a phenyl alkyl ether (methyl phenyl ether).
Why the other options are incorrect
Option (1) Dialkyl ether — Incorrect. This needs two alkyl groups, as in ethoxyethane; anisole has a phenyl group on one side.
Option (2) Diaryl ether — Incorrect. This needs two aryl groups, as in diphenyl ether; anisole has only one.
Option (4) Alkoxy Alkyl ether — Incorrect. There is no such class of ethers; an alkoxy group is itself the R–O– part of an ether.
Note: It seems that there is a mistake in the original NTA paper, which prints alkoxy or carboxyl group when it should read alkoxy or aryloxy group, and deactivates when it should read activates.
NCERT (2026-27 edition):
Ethers – “Ethers are classified as simple or symmetrical, if the alkyl or aryl groups attached to the oxygen atom are the same, and mixed or unsymmetrical, if the two groups are different. Diethyl ether, \( \ce{C2H5OC2H5} \), is a symmetrical ether whereas \( \ce{C2H5OCH3} \) and \( \ce{C2H5OC6H5} \) are unsymmetrical ethers.”
Halogenation – “Phenylalkyl ethers undergo usual halogenation in the benzene ring, e.g., anisole undergoes bromination with bromine in ethanoic acid even in the absence of iron (III) bromide catalyst. It is due to the activation of benzene ring by the methoxy group. Para isomer is obtained in 90% yield.”