If the NMR spectrum indicates the presence of impurities, probably 2-acetylnaphthalene, convert the substance to its picrate by dissolving in *benzene or EtOH and adding excess of satd-picric acid in these solvents until separation of picrates is complete. Recryst the picrate till m is 118°C. Decompose the picrate with dil NaOH and extract with Et₂O. Dry the extract (Na₂SO₄), filter, evap and dist. The 2,4-dinitrophenyfhydruzohydrazone crysts from EtOH and has m 259°C.