Question

Write the IUPAC names of phenols given:
(i)-

(ii)-

Answer 1

Hint: Phenols are those compounds in which there is a hydroxyl group present on the benzene ring. In option (i), the other two substituents are nitro and methyl groups, and in option (ii), there are two hydroxyl groups and one methyl group present on the benzene ring. While naming the compound, the methyl group will be named in the prefix part.

Complete answer:
There are many aromatic compounds in which phenols are those in which there is a hydroxyl group present on the benzene ring.
While naming in the IUPAC, we have to see which group should be given preference. The group that is given preference is named in the suffix part.
In option (i), there are two substituents on the phenol molecule, these are the nitro group and the methyl group.

The nitro group is on the ortho or 2nd position of the phenol, while the methyl group is on the para or 4th position of the phenol. While naming the methyl group will be named first and the nitro group will be named later. So, the name will be 4-Methyl-2-nitrophenol.
In option (b), there are two hydroxyl groups and one methyl, so in this molecule, one hydroxyl group is present in the 1st position, the other hydroxyl group is in the 2nd position and the methyl group is present in the 4th position.

So, its name will be 4-methyl benzene-1, 2-diol.

Note:
While naming the aromatic compound, the 2nd position can also be named as ortho, the 3rd position can also be named as meta, and the 4th position can also be named as para.