Question

Which of the following is an example of primary amine?

• A. N-methyl aniline
• B. N-phenylbenzenamine
• C. Methyl phenylamine
• D. Isopropyl amine

Hint:

When scanning IUPAC or common names for primary amines, look for the suffix or functional term "amine" without any "N-" prefixes. Simple mono-alkyl naming patterns like [Alkyl]amine always designate a primary ($1^\circ$) amine with an intact $-\mathrm{NH_2}$ group.

Answer 1

The Correct Option is D

Step 1: Pin down primary amine.
A primary ($1^\circ$) amine has nitrogen carrying exactly one carbon group and a free $-NH_2$ with two hydrogens.
Step 2: Build a one line test.
Count carbons directly on nitrogen. One carbon means primary, two means secondary, three means tertiary.
Step 3: Check N-methyl aniline.
Structure $C_6H_5-NH-CH_3$ has both a phenyl and a methyl on nitrogen, so two carbons, that is secondary, reject.
Step 4: Check N-phenylbenzenamine.
This is diphenylamine $(C_6H_5)_2NH$ with two phenyl groups on nitrogen, again secondary, reject.
Step 5: Check methyl phenylamine.
This is just another name for N-methylaniline, two carbons on nitrogen, secondary, reject.
Step 6: Check isopropyl amine and conclude.
Structure $(CH_3)_2CH-NH_2$ has only one carbon group on nitrogen and an intact $-NH_2$, so it is primary.
\[ \boxed{\text{Isopropyl amine (option D)}} \]