Question

What is the correct IUPAC name for a molecule that has two amino groups in opposing (para) locations around a benzene ring?

• A. Benzenediamine
• B. Benzene-1,4-diamine
• C. p-Aminoaniline
• D. 4-Aminobenzenamine

Hint:

Number the ring so the two amino groups get the lowest locants: 1,4.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
When benzene carries two identical principal groups, the name uses the suffix with a multiplying prefix and locants, such as benzene-1,4-diamine.

Step 2: Detailed Explanation
The para positions are carbon 1 and carbon 4. The parent is benzene, the groups are two \(\text{-NH}_2\) groups, so the name is benzene-1,4-diamine.
(A) Benzenediamine has no locants, so it does not say which positions. (C) p-Aminoaniline is a common-style name, not IUPAC. (D) 4-Aminobenzenamine is not the preferred IUPAC form for two identical groups.

Final Answer:
The correct IUPAC name is benzene-1,4-diamine, option (B). \[ \boxed{\text{Benzene-1,4-diamine}} \]