Question

Classify the following amines as primary, secondary or tertiary: [H]

Hint:

Look strictly at the nitrogen atom: 2 Hydrogens = Primary. 1 Hydrogen = Secondary. 0 Hydrogens = Tertiary.

Answer 1

Step 1: Concept
Classification of amines based on the degree of nitrogen substitution.

Step 2: Meaning
A primary ($1^\circ$) amine has one carbon attached to nitrogen. A secondary ($2^\circ$) amine has two. A tertiary ($3^\circ$) amine has three.

Step 3: Analysis
(i) In N,N-dimethyl-2-naphthylamine, the nitrogen atom is bonded to three carbon atoms: two from the distinct methyl groups and one from the naphthyl ring. It has zero N-H bonds. Thus, it is a tertiary amine.
(ii) In 2-naphthylamine, the nitrogen atom is bonded to only one carbon atom (from the naphthyl ring) and has two N-H bonds. Thus, it is a primary amine.

Step 4: Conclusion
The number of C-N bonds directly defines the class of the amine.

Final Answer:
(i) Tertiary ($3^\circ$) amine
(ii) Primary ($1^\circ$) amine