Amines

(a) Stability due to resonance and delocalization of over benzene ring. (b) Aniline forms a Lewis acid–base complex with AlCl → deactivates ring. (c) In acidic medium, aniline gets protonated to , a meta-directing group.

- Ethanamine is an aliphatic primary amine. - Aniline is an aromatic primary amine. **Azo dye test** is a specific test used to detect aromatic primary amines. In this test: - Aniline reacts with nitrous acid (generated in situ from NaNO + HCl) to form a diazonium salt. - This diazonium salt couples with phenol or β-naphthol to form a bright-colored azo dye. Ethanamine (an aliphatic amine) does not form a stable diazonium salt and hence does **not** give this test.

- Aniline ( ) is more basic than acetanilide ( ). - In acetanilide, the lone pair of electrons on nitrogen is delocalized due to resonance with the carbonyl group of the acetyl group ( ). This delocalization reduces the availability of the lone pair on nitrogen for protonation, hence decreasing basicity. So: - Assertion is true — acetanilide is less basic than aniline. - Reason is also true — acetylation pulls electron density away from nitrogen. - And Reason correctly explains the Assertion.

Basicity in gaseous phase is determined by electron-donating ability of alkyl groups which increase electron density on nitrogen. The more alkyl groups attached, the higher the basicity: - NH : No alkyl group - CH NH : One methyl group - (CH ) NH: Two methyl groups - (CH ) N: Three methyl groups Hence, basicity order increases as: Note: This is valid for gaseous phase. In aqueous phase, steric hindrance and solvation affect order.