Sulfuric Acid → HCID 20328055, compound

Participants

Reaction Conditions

Reaction Steps

To a suspension of 3,4-dibromo-β-methylpyrazole-1-ethanol (2.8 g., 0.01 mole) prepared in Example 38, above, in sodium hydroxide (0.3 g., 0.0075 mole) and water (3.0 ml.), a solution of potassium permanganate (3.4 g., 0.0215 mole) in water (30 ml.) was added over a period of 20 minutes. A further 30 ml. of water was added and the reaction mixture was stirred at about 25° C. for 4 hours, followed by acidification with 6N sulfuric acid and addition of sodium bisulfite until all the precipitated manganese dioxide went into solution. The aqueous solution was extracted with three 50-ml. portions of ether and the combined ether extracts were washed with water and dried over anhydrous sodium sulfate. Evaporation of the ether under reduced pressure followed by chromatography on silica gel using the solvent system benzene, 85:chloroform, 5:glacial acetic acid, 10 (by volume) gave a solid which on recrystallization from acetone-hexane gave 3,4-dibromo-α-methylpyrazole-1-acetic acid having a melting point at 124.5° to 126.5° C.

Provenance & Evidence