Chlorodifluoromethane → 2-Chloro-4-fluoro-5-[4-(difluoromethyl)-4,5-dihydro-3-methyl-5-oxo-1H-1,2,4-triazol-1-yl]-benzoic Acid Methylester

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Reaction Steps

An excess of chlorodifluoromethane (97 g) was bubbled into a mixture of triazolinone from step 2 (7.04 g, 24.6 mmol), tetrabutylammonium bromide (9.67 g, 30.0 mmol), potassium carbonate (16.6 g, 122 mmol) and dimethylformamide (200 ml) in such a way that T<36° C. over a period of 30 minutes. The mixture was cooled and filtered. The filtrate was concentrated under reduced presssure and the residue partitioned between water and methylene chloride. The organic layer was washed with water, dried and concentrated under reduced pressure to give a dark oil (9.00 g), which was chromatographed on silica gel (eluent: ethyl acetate/hexane) to give the title compound. Yield: 1.48 g (17.9%).

Provenance & Evidence