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

To 3,4,5-tribromopyrazole (4.5 g, 0.15 mole) in 3 N 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° C. to 86° C. Crystallization from cyclohexane gives desired solid product whose melting point ranges from 90° C. to 91° C.

1. filtrationfiltered
2. washthe precipitate water washed
3. customair dried
4. customto yield 33 g (73%), mp 85° C. to 86° C
5. customCrystallization from cyclohexane
6. customgives desired solid product whose
7. customranges from 90° C. to 91° C.

ORD record

ord-375a112782c145f8901647445a9c3010

Source dataset

uspto-grants-1977_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04029492