(CAS NO. ) is purified by dissolving (10g) in the minimum volume of CHCl₃ (ca 25mL) filtered, and diluted with five volumes (i.e. 125mL) of pet ether (b 30-60°C) to precipitate impurities. The soln is filtered, clarified with charcoal and concentrated to 40 mL by evaporation. Further evaporation to a very small volume gave 7g of white crystals which were analytically pure, m 67.5-68.5 °C. (The insoluble material was largely tosic acid and had m 101-104°C).

It is also crystd from toluene/pet ether in the cold, from pet ether (b 40-60 °C) or benzene. Its soln in diethyl ether has been washed with aqueous 10 % NaOH until colourless, then dried (Na₂SO₄) and crystd by cooling in powdered Dry-ice. Tosyl chloride has also been purified by dissolving in benzene, washing with aqueous 5% NaOH, then dried with K2CO₃ or MgSO₄, and distd under reduced pressure and can be sublimed at high vacuum.