P-chloroaniline and anilinium hydrochloride can be...

p-chloroaniline and anilinium hydrochloride can be distinguished by
1. Sandmeyer reaction
2. $\mathrm{NaHCO}_{3}$
3. $\mathrm{AgNO}_{3}$
4. Carbylamine test
(a) $1,2,4$
(b) $1,2,3$
(c) $1.3 .4$
(d) $1.2$

Key Concepts

Diazotization and Sandmeyer Reaction

Diazotization converts a primary aromatic amine into a diazonium salt, which can then participate in the Sandmeyer reaction to substitute the diazonium group with various nucleophiles. However, the formation of a diazonium salt generally requires acidic conditions that protonate the amine; thus, while the Sandmeyer reaction is a key reaction in aromatic substitution chemistry, it may not clearly distinguish between a free amine and its already protonated counterpart unless additional steps are taken.

Halide Ion Precipitation Test

A halide ion test using silver nitrate is based on the ability of free chloride ions to form insoluble silver chloride precipitate. An ammonium salt like anilinium hydrochloride contains a counter chloride ion that will precipitate upon addition of AgNO3, whereas the free amine (which does not bring a chloride ion into solution) will not give this result.

Carbylamine Test

The carbylamine test is a qualitative reaction used to detect primary amines. In the presence of chloroform and a base, a free primary amine reacts to form an isocyanide, which has a characteristic foul odor. However, when the amine is in its protonated (ammonium salt) form, the test does not proceed because the essential free lone pair on the nitrogen is not available for reaction.

Acid?Base Properties of Aromatic Amines

Aromatic amines, such as aniline derivatives, are weak bases that can exist either as free amine bases or as their protonated ammonium salts. Their basicity affects how they react in various chemical tests. When protonated (as in anilinium salts), the lone pair on the nitrogen becomes tied up, altering the chemical reactivity compared to the free base form.

Please give Ace some feedback