Distinction between pairs of compounds
Ethylamine `(CH_(3)CH_(2)NH_(2))` and diethylamine `(CH_(3)CH_(2)NHCH_(2)CH_(3))`

Explanation

Following tests help to distinguish these :
(a) When ethylamine (primary amine) is heated with chloroform and alcoholic KOH, ethyl isocyanide (carbylamine) of offensive smell is formed. Diethylamine does not give this test.
`underset("Ethylamine")(CH_(3)CH_(2)NH_(2))+CHCl_(3)+3KOH(alc)rarrundersetunderset(("offensive smell"))("Ethyl Isocyanide")(CH_(3)CH_(2)Noverset(=)rarrC)+3KCl+3H_(2)O`
(b) When ethylamine is treated with Hinsberg.s reagent, N-ethylbenzenesulfonamide (soluble in KOH) is formed. Diethylamine gives N, N-Diethylbenzenesulfonamide (insoluble in KOH) is formed.
`C_(6)H_(5)SO_(2)Cl+CH_(3)CH_(2)NH_(2)rarrundersetunderset(("Soluble in KOH"))("N-Ethylbenzensulfonamide")(C_(6)H_(5)SO_(2)-NHCH_(2)CH_(3)+HCl)`
`overset(KOH)rarr[C_(6)H_(5)SO_(2)-barNCH_(2)CH_(3)]K^(+)+H_(2)O`
`C_(6)H_(5)SO_(2)Cl+CH_(3)CH_(2)NHCH_(2)CH_(3)rarrundersetunderset(("Insoluble in aq. KOH"))("N-N-Diethylbenzenesulfonamide")(C_(6)H_(5)SO_(2)N(CH_(2)CH_(3))_(2)+HCl)`