Question

Which of the following is a secondary amine?

• A. Cyclohexylamine
• B. Isopropylamine
• C. Diphenylamine
• D. N, N-Dimethylaniline

Hint:

To quickly classify an amine, count the number of hydrogen atoms attached to the nitrogen. Two H's = Primary. One H = Secondary. Zero H's = Tertiary. (This trick works for simple, non-quaternary amines).

Answer 1

The Correct Option is C

Step 1: Define the classes of amines.
Amines are classified based on the number of alkyl or aryl groups directly bonded to the nitrogen atom.
- Primary (1\(^\circ\)) amine: One carbon group attached to nitrogen (general formula R-NH\(_2\)).
- Secondary (2\(^\circ\)) amine: Two carbon groups attached to nitrogen (general formula R\(_2\)-NH).
- Tertiary (3\(^\circ\)) amine: Three carbon groups attached to nitrogen (general formula R\(_3\)-N).
Step 2: Classify each option.
- Cyclohexylamine: The nitrogen is attached to one cyclohexyl group. It is a primary amine (C\(_6\)H\(_{11}\)-NH\(_2\)).
- Isopropylamine: The nitrogen is attached to one isopropyl group. It is a primary amine ((CH\(_3\))\(_2\)CH-NH\(_2\)).
- Diphenylamine: The nitrogen is attached to two phenyl groups. It is a secondary amine ((C\(_6\)H\(_5\))\(_2\)NH). - N, N-Dimethylaniline: The nitrogen is attached to one phenyl group and two methyl groups, for a total of three carbon groups. It is a tertiary amine.
Therefore, diphenylamine is the secondary amine.