14990-02-4

Recrystallise it from xylene; chromatograph it on basic silica gel (60-80 mesh) using CH2Cl2 as eluent, then sublime it in a vacuum on to a cold surface at 10-3torr [Ebied J Chem Soc, Faraday Trans 1 78 3213 1982]. All operations should be carried out in the dark.