1457-42-7

Purify the oxide by distillation in a vacuum and by sublimation in vacuo. When a solution of the oxide in MeOH is treated with an aqueous solution of CuCl2, the [C4H4N2O]2—CuCl2-2H2O-complex (m 182-183o) is formed from which the oxide can be recovered . [Pollak et al. J Org Chem 35 2478 1970, Klinge et al. Recl Trav Chim, Pays Bas 95 21 1976, Ohsawa et al. Tetrahedron Lett 1979 1978, Koelsch & Gumprecht J Org Chem 23 1605 1958, Beilstein 23 III/IV 890.]