Dissolve it in Et2O, wash it with aqueous alkali, then H2O and dry it. Evaporate the ether and recrystallise it from EtOH to give pure material. It gives yellow crystals from pet ether ( m 109o, 110o). [Beilstein 9 H 391, 9 II 258, 9 III 1543, 9 IV 1075.]
