Dimethyl Sulfate → 3,4,5-Tribromo-1-methyl-1H-pyrazole

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Reaction Steps

To 3,4,5-tribromopyrazole (4.5 g, 0.15 mole) at 3N aqueous sodium hydroxide (6 g, 0.15 mole) is added at room temperature with stirring dimethyl sulfate (19 g, 0.15 mole). After 10 minutes a solid separates out. An additional gram (0.0079 mole) of dimethyl sulfate is added and the mixture is stirred for 3 days, filtered, and the precipitate water washed and air dried to yield 33 g (73%), mp 85° to 86° C. Crystallization from cyclohexane gives desired solid product whose melting point ranges from 90° to 91° C.

Provenance & Evidence