Potassium Carbonate → 4-(Pentafluorophenyl)urazole

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4-(Pentafluorophenyl)-1-carbethoxysemicarbazide, 2.13 g (0.0068M), and potassium carbonate, 0.938 g (0.0068M), are added to 75 ml of water. The mixture is heated at 70° C. under N2 about 12 hours. The solution is cooled in an ice bath and filtered to remove a trace of starting material. The pH of the solution is adjusted to pH 7 with concentrated HCl and extracted with ethyl acetate to remove a product which is less polar than the urazole in the TLC system, chloroform/ethyl acetate/acetic acid (5/5/1). The pH of the solution is reduced to 1 or 2 with concentrated HCl and then extracted with ethyl acetate. About 1/3 of a volume of toluene is added to the ethyl acetate and the solvents evaporated. The resulting crude solid weighs 0.569 g. The product is purified by two crystallizations from ethyl acetate/toluene (1/3 by vol). The yield of purified material is 0.476 g. It is recrystallized from H2O, mp 223°-225°.

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