In general, the methods of purifying (CAS NO. ) are similar to those for purifying aniline can be used. It can be separated from the 0- and m-isomers by fractional crystn from its melt. p-Toluidine has been crystd from hot water (charcoal), EtOH, benzene, pet ether or EtOH / water (1:4), and dried in a vacuum desiccator. It can also be sublimed at 30 °C under vacuum. For further purification, use has been made of the oxalate, the sulfate and acetylation. The oxalate, formed as described for o-toluidine, was filtered, washed and recrystd three times from hot distd water. The base was regenerated with aq Na₂CO₃ and recrystd three times from distd water.

Alternatively, p-toluidine was converted to its acetyl derivative which, after repeated crystn from EtOH, was hydrolysed by refluxing (50g) in a mixture of 500mL of water and 115mL of conc H₂SO₄ until a clear soln was obtained. The amine sulfate was isolated, suspended in water, and NaOH was added. The free base was distd twice from zinc dust under vacuum. The p-toluidine was then recrystd from pet ether and dried in a vacuum desiccator or in a vacuum for 6h at 40 °C.