Phenylbutazone → 1,2-Diphenyl-4-butyl-5(4'-methylphenylsulfonyloxy)-4-pyrazolin-3-one

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Reaction Steps

Then, p-Toluenesulfonyl chloride (0.95 g, 5.0 mmole) was allowed to react with a dimethylformamide (20 ml) suspension of the Thallium (I) salt of phenylbutazone. Within a few minutes the solvent became pink and a yellow solid, instead of the white Thallium (I) salt of phenylbutazone, was observed suspended in the pink solution. The suspension was stirred overnight in a tightly sealed flask, then it was diluted with 100 ml of ether and filtered. The filtrate was concentrated in vacuo to remove the ether and the dimethylformamide was evaporated under a stream of nitrogen. The residue from the evaporation was suspended in dichloromethane and filtered. Analysis of the filtrate by TLC showed that it contained only one major component. The dichloromethane was evaporated in vacuo and the residue was crystallized from ether to give 0.76 g (mp 112°-121° C., 33% yield) of yellow crystals which contained only one component by TLC analysis. Recrystallization of the yellow crystals gave analytically pure crystals, mp 125°-127° C. with spectral properties identical to the crystals, mp 112°-121° C.

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