Discuss one method by' which we can separate p-hydroxybenzoic acid and p-aminobenzoic acid from a mixture of the two and write down the confirmatory tests of the functional group.

Explanation

The mixture is treated with dil.HCl when p-aminobenzoic acid forms the sa< leaving p-hydroxy benzoic acid. The mixture is then extracted with éther
figure
when p-hydroxy bénzoic acid is ín the ether layer and p -aminobenzoic acid is obtained in the aqueous medium.
Confirmatory tests for functional group
(i) p-hydroxy benzoic acid gives violet colouration with 'FeCl', due to the presence of phenolic group.
(ii) p-amino benzoic acid contains '1^circ' aromatic amino group, it gives both carbylamine reaction and azodye test.
(iii) Both the acids react with 'NaHCO_3' solution to " produce brisk effervescence due to the evolution of 'CO_2'