Give a chemical test for differentiating the following couple of compounds: (i) Secondary and tertiary amines (ii) Methyl amine and dimethyl amine (iii) Ethylamine and aniline.

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> [!TLDR]
> Use Hinsberg's reagent for $2^\circ$ vs $3^\circ$; the carbylamine (isocyanide) test for a $1^\circ$ vs $2^\circ$ amine; and the diazotisation–coupling (azo-dye) test for an aromatic ($aniline$) vs aliphatic ($ethylamine$) amine.
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> **(i) Secondary vs tertiary amine (Hinsberg test):** Treat with **benzenesulphonyl chloride** ($C_6H_5SO_2Cl$).
> - A $2^\circ$ amine gives a sulphonamide with **no N–H**, which is **insoluble in KOH** (a precipitate forms).
> - A $3^\circ$ amine has **no replaceable H and does not react**.
> So a KOH-insoluble product $\Rightarrow 2^\circ$; no reaction $\Rightarrow 3^\circ$.
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> **(ii) Methylamine ($1^\circ$) vs dimethylamine ($2^\circ$) — carbylamine test:** Warm with $CHCl_3$ and alcoholic $KOH$.
> $$CH_3NH_2 + CHCl_3 + 3KOH \rightarrow CH_3NC + 3KCl + 3H_2O$$
> Methylamine (a **primary** amine) gives **methyl isocyanide, a foul-smelling** product. Dimethylamine (**secondary**) gives **no such smell** — it does not respond to the carbylamine test.
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> **(iii) Ethylamine vs aniline — azo-dye test:** Add cold $NaNO_2 + HCl$ (diazotisation), then alkaline $\beta$-naphthol. …

Observation	What it means
Clear solution forms	Primary amine (soluble salt)
Solid precipitate forms	Secondary amine (insoluble sulfonamide)
Oily layer remains, no precipitate	Tertiary amine (no reaction)

Q.Give a chemical test for differentiating the following couple of compounds:

Concept understanding — Hinsberg Test

The Hinsberg Test: Distinguishing Amines by Reactivity

What Actually Happens

The Practical Workflow

Why This Works — The Key Insight …

Q.Give a chemical test for differentiating the following couple of compounds:

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