Phosphorus oxychloride → 2,5-Dichloro-1,1,1,6,6,6-hexafluoro-3,4-diazahexa-2,4-diene

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Reaction Steps

A mixture of N,N-diethylaniline hydrochloride (18.5 g, 0.1 mol), 1,2-bis(trifluoroacetyl)hydrazine (10.3 g, 0.46 mol) and phosphoryl chloride (160 mL) was stirred for 30 minutes under nitrogen in a flask fitted with a condenser leading to a cold trap (−78° C.). The mixture was heated under reflux for 5 h and then allowed to cool and stored overnight. The flask contents and the small amount of material which had condensed in the cold trap were combined and the two layers which had formed were separated. The layer was added to ice water (85 mL) and the mixture vigorously stirred for 1 h in a flask fitted with a condenser. Separation of the lower organic layer gave the main batch of the crude product (6.4 g). The original dark upper layer was treated similarly with ice water (75 mL) and the organic layer subjected to preliminary purification by trap-to-trap distillation in vacuum to afford a second batch of crude product (1.6 g). Distillation of the combined product through a vacuum-jacketed Vigreux column gave 2,5-dichloro-1,1,1,6,6,6-hexafluoro-3,4-diazahexa-2,4-diene (6.3 g, 53%) as an oil.

Provenance & Evidence