The following is to be carried out in an efficient FUME HOOD. Dissolve the compound (180g) in CS2 (500 mL) by refluxing for 15minutes (to cause the separation of the most likely impurity, 1,2-diphthalimidoethane), filter and evaporate under reduced pressure. The product forms light tan crystals (m 78-80o). Recrystallise it from EtOH (charcoal) [the compound (50g) is dissolved in hot 75% EtOH (200mL), boiled for ca 10 minutes, carbon is added (5g, Norite), filter and cool to 0o], to give white crystals (40g) which can be recrystallised (m 80-81o); and further recrystallisation gives m 82-83o. [Salzberg & Supniewski Org Synth Coll Vol I 119 1932, Landini & Rolla Synthesis 389 1976, Beilstein 21/10 V 275.]
