Question

The IUPAC name of the following compound is

• A. \(5\text{-Methyl-}3\text{-aminophenol}\)
• B. \(3\text{-Amino-}5\text{-methylphenol}\)
• C. \(3\text{-Amino-}5\text{-hydroxy\ toluene}\)
• D. \(3\text{-Hydroxy-}5\text{-methylaniline}\)

Hint:

In IUPAC nomenclature, the functional group with highest priority determines the parent name and gets the lowest possible locant.

Answer 1

The Correct Option is B

Step 1: Identify the functional groups on the benzene ring.
The compound has three groups: \( -OH \) (hydroxyl), \( -NH_2 \) (amino), and \( -CH_3 \) (methyl).
Step 2: Determine the principal characteristic group.
In IUPAC priority order, \( -OH \) on benzene is chosen as the principal group. The parent compound is phenol, with \( -OH \) at carbon 1.
Step 3: Number the ring to give lowest locants.
Carbon 1 carries \( -OH \). Numbering to give the lowest locant set places \( -NH_2 \) at C-3 and \( -CH_3 \) at C-5 (locant set {1, 3, 5}).
Step 4: Name the substituents.
\( -NH_2 \) at C-3 is named 3-amino. \( -CH_3 \) at C-5 is named 5-methyl.
Step 5: Combine the name in alphabetical order of prefixes.
Amino comes before methyl alphabetically. Full IUPAC name: 3-amino-5-methylphenol.
Step 6: Match with options.
Option 2 is 3-Amino-5-methylphenol. \[ \boxed{3\text{-Amino-}5\text{-methylphenol}} \]