Question

Propose a method to separate a mixture containing phenol, benzoic acid, naphthalene, and p-nitro aniline. Phenol is soluble in sodium hydroxide solution but insoluble in neutral water or sodium bicarbonate solution. Benzoic acid is soluble in either sodium hydroxide or sodium bicarbonate solutions. Write out the structures of the molecules in your scheme.

Answer 1

Dissolve the mixture in diethylether or some similar organic solvent. Then using a separating funnel add an aqueous solution of sodium hydroxide. The phenol and benzoic acid will react with the base to form phenolate and benzoate ions that will dissolve into the water layer. Again Re precipitate the organic molecules by adding concentrated hydrochloric acid. The phenol and benzoic acid can be separated by heating the mixture in water to dissolve the fan on and then filtering of the insoluble benzoic acid. The solution can then be acidified to return the phenol. Now we can add a solution of hydrochloric acid to the separating funnel which will react with the basic aniline dissolving it into the water. By collecting the aqueous layer And re precipitating the anniline with excess sodium hydroxide and boiling the remaining organic solvent will left behind the napthalene which was left untouched by all the acids and bases.