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: Understanding the Question:
The problem requires us to evaluate the given chemical options and identify which compound represents a primary ($1^\circ$) amine structural configuration.

Step 2: Key Formula or Approach:
Amines are structurally classified based on the number of organic carbon substituents covalently bound to the central nitrogen atom:

• Primary amine ($1^\circ$): The nitrogen atom is bound to exactly one carbon group and retains two hydrogen atoms ($-\mathrm{NH_2}$).

• Secondary amine ($2^\circ$): The nitrogen atom is bound to two carbon groups and retains one hydrogen atom ($-\mathrm{NH-}$).

• Tertiary amine ($3^\circ$): The nitrogen atom is bound to three carbon groups and has no remaining hydrogens ($-\mathrm{N-}$).

Step 3: Detailed Explanation:
Let's analyze the structures of the given options:

• N-methyl aniline: A compound where a methyl group and a phenyl ring are both attached to the nitrogen atom ($\mathrm{C_6H_5-NH-CH_3}$). This is a secondary ($2^\circ$) amine.

• N-phenylbenzenamine: Also known as diphenylamine, it features two phenyl rings bound to the nitrogen atom ($\mathrm{(C_6H_5)_2NH}$). This is a secondary ($2^\circ$) amine.

• Methyl phenylamine: An alternative name for N-methylaniline, which is a secondary ($2^\circ$) amine.

• Isopropyl amine: Features a single isopropyl group attached to an amino functional group ($\mathrm{(CH_3)_2CH-NH_2}$). Because the nitrogen atom is bonded to only one alkyl carbon atom and contains a free $-\mathrm{NH_2}$ group, it is classified as a primary ($1^\circ$) amine.

Step 4: Final Answer:
The example of a primary amine is Isopropyl amine, corresponding to option (D).