3-bromo-4-ethoxy-1,1,1-trifluorobut-3-en-2-one

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2.3 g (0.01 mole) of 3-bromo-4-ethoxy-1,1,1-trifluorobut-3-en-2-one are added to a solution of 4.2 g (0.02 mol) of 2,4,6-trichlorophenyl-hydrazine in 100 ml of ethanol which contains 0.01 mole hydrogen bromide. The mixture is refluxed for 5 hours and then concentrated under reduced pressure, and ice water is added to the residue. Extraction with dichloromethane, washing with saturated sodium chloride solution until neutral, clarification over anhydrous sodium sulphate and concentration gives 4.6 g of a crude product, which is chromatographed on 120 g of silica gel using toluene/petroleum ether (ratio 1:1). 1.2 g of 4-bromo-1-(2,4,6-trichloro-phenyl)-3-trifluoromethylpyrazole of melting point 93°-94° C. (from petroleum ether) are obtained. The mixture is refluxed for 5 hours concentrated under reduced pressure, and ice water is added to the residue Extraction with dichloromethane washing with saturated sodium chloride solution until neutral, clarification over anhydrous sodium sulphate and concentration gives 4.6 g of a crude product, which is chromatographed on 120 g of silica gel

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 9.8 g (0.055 mole) of N-bromosuccinimide and 100 mg azoisobutyronitrile are added to a solution of 8.4 g (0.05 mole) of 4-ethoxy-1,1,1-trifluoro-but-3-en-2-one in 50 ml of tetrachloromethane. The mixture is then refluxed for 8 hours, the cooled solution is filtered and the filtrate is concentrated. 13.4 g of a crude product are obtained whiose distillation under reduced pressure gives 9.7 g of 3-bromo-4-ethoxy-1,1,1-trifluorobut-3-en-2-one. The mixture is then refluxed for 8 hours the cooled solution is filtered the filtrate is concentrated 13.4 g of a crude product are obtained whiose distillation under reduced pressure