H. Egg. J.Hauzinger, K.Kraus, and E. Spanyar, Synth. Commun., 22, 1199 (1992)

1. A stirred solution of 4-bromophenylhydrazine (0.01 mol) and DMAP (0.001 mol) in dry pyridine (10 mL) is prepared and cooled to 0°C.  Acetic anhydride (0.02 mol) is added; the solution is allowed to warm to ambient temperature and is stirred for a further 12 h.
2. The reaction mixture is poured into 2 N hydrochloric acid (100 mL) and extracted with dichloromethane (3 x 50 mL). The combined methylene chloride solution is evaporated to yield an oily residue which is purified by preparative medium pressure liquid chromatography on silica (eluent ether) to afford N,N-diacetyl-2-(4-bromophenyl)hydrazide (1.98 g, 73%, m.p. 101°C).