Phosphorus oxychloride → (5-Chloro-1-methyl-1H-pyrazol-4-yl)(2,4-dichlorophenyl)methanone

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Reaction Steps

To 5 ml of phosphorus oxychloride was added 2.71 g (0.01 mol) of 4-(2,4-dichlorobenzoyl)-1-methyl-5-hydroxypyrazole and the resulting mixture was heated under reflux for 3 hours. After cooling, the reaction mixture was poured into ice water. Oily product was extracted with ethyl acetate, washed successively with 5% aqueous sodium bicarbonate and saturated brine and dried over anhydrous sodium sulfate. Then the solvent was distilled off therefrom under reduced pressure and the resulting oil was purified through silica gel column chromatography using benzene as an eluant to give 2.84 g of the title compound as pale yellow crystals, (yield: 98%), m.p. 81.0°-83.0° C.

Provenance & Evidence