Phosphorus oxychloride → N'-(2,6-dichloro-4-trifluoromethylphenyl)-chloroacetohydrazonoyl chloride

Phosphoryl chloride (500 microlitres, 1.7 equivalents) was added in one portion to a stirred solution of N′-(2,6-dichloro-4-trifluoromethylphenyl)-chloroacetohydrazide (1.0 g, 3.11 mmol) in toluene (20 ml) and heated at 70° C. under an argon atmosphere for 20 hours. The cooled mixture was evaporated and the residue extracted with cyclohexane. The extracts were combined and evaporated to give the title compound (0.971 g) as an orange oil, NMR 4.4(s,2H), 7.55(s,2H), 7.7(s,1H). The yield was 90%.