Purification Methods
Purify it by recrystallisation from diisopropyl ether or pet ether and dry it in air. If too impure, then dissolve it in Et2O, wash with aqueous NaHCO3, then H2O, dry (MgSO4), filter, evaporate and the residue is recrystallised as before. [Cardwell J Chem Soc 715 1949.] The oxime can be recrystallised from CHCl3/pet ether (at -20o) and has m 84-85o [Barkenbus et al. J Org Chem 20 871 1955]. The 2,4-dinitrophenylhydrazone has m 186o (from EtOAc) [Barkenbus et al. J Org Chem 16 232 1951]. The S-dioxide is recrystallised from AcOH, m 173-174o [Fehnel & Carmack J Am Chem Soc 70 1813 1948, Beilstein 17 II 287, 17 III/IV 4172, 17/1 V 21].
