3-(Difluoromethyl)-1-methyl-1 H-pyrazole-4-carbonyl chloride → Fluxapyroxad

Participants

Reaction Conditions

Reaction Steps

9.55 kg 3′,4′,5′-trifluoro[1,1′-biphenyl]-2-yl-amine (I) were dissolved in 51.4 kg and 6 kg pyridine were added. The mixture was stirred at 45° C. and 8.3 kg 3-(difluoromethyl)-1-methyl-1H-pyrazole-4-carbonyl chloride (II) were dosed during one hour. Due to the exothermic nature of the reaction, the temperature raised to 55° C. Post-reaction by stirring for 1 hour at 55° C. followed. Three extractions at 85° C. with 16 liter hydrochloric acid (5%), 14 liter sodium hydrogen carbonate (8%), and 14 liter deionized water followed. The resulting clear solution in toluene was cooled from 85° C. with a rate of 10° C. per hour to 0° C. Around 75° C., the first turbidity was observed, and at 75° C. and 73° C., respectively, the batch was seeded with 10 g 3-(difluoromethyl)-1-methyl-N-(3′,4′,5′-trifluoro[1,1′-biphenyl]-2-yl)-1H-pyrazole-4-carboxamide (III) each (>98% form B). The resulting slurry was filtered at 0° C. over a process filter and the filter cake was washed with 10 kg toluene at 0° C. After drying in the drying cabinet at 80° C. and 20 mbar for 12 hours, 13.5 kg 3-(difluoromethyl)-1-methyl-N-(3′,4′,5′-trifluoro[1,1′-biphenyl]-2-yl)-1H-pyrazole-4-carboxamide (III) of >99.5% purity (GC, HPLC, NMR) was isolated. Using powder diffractometry (PXRD) and Fourier-Transform solid state infrared spectrometry (FT-IR) it was proven that the material consists to >98% of form B.

Provenance & Evidence