Sodium Hydroxide → HCID 21536642、化合物

A quantity (5.1 g., 0.015 mole) of the ethyl 3,4 -dibromo-α,5-dimethylpyrazole-1-acetate prepared in Part A, above, was added to a solution consisting of 0.8 g. (0.02 mole) sodium hydroxide in 100 ml. water and the resulting suspension was heated at the reflux temperature for 3 hrs. A clear, aqueous solution resulted. The aqueous solution was extracted with 50 ml. diethyl ether and the ether extract was discarded. The ether-extracted aqueous layer was then adjusted to pH 2 with 1.5 N hydrochloric acid and again extracted three times with 40 ml. portions of the ether. These ether extracts were combined, washed with three, 30 ml. portions of water, dried over anhydrous magnesium sulfate, and the ether was removed by evaporation under reduced pressure. There was thus obtained 4.0 g. (85% yield) of 3,4 -dibromo-α, 5-dimethylpyrazole-1-acetic acid having a melting point at 131° to 135.5° C. Recrystallization from a mixture of acetone and hexane gave the compound with a melting point at 138° C.