Sulfuric Acid → Ketoprofen

Participants

Reaction Steps

α-(3-(1-Phenylethenyl)propionic acid methyl ester (36 g) obtained in Example 7 was dissolved in 250 ml of benzene and 250 ml of water was further added thereto with vigorous stirring to prepare a suspension. Then, 2 liter of 2% aqueous solution of potassium permanganate was dropped little by little over 1.5 hours. After the dropping, stirring was continued for 18 hours at room temperature. After the reaction, the reaction mixture was acidified by adding concentrated sulfuric acid and was treated by adding 35 g of sodium sulfite. After that, 500 ml of water was added and extraction was carried out three times with 150 ml of ether. The ether solution was washed with water. The remaining layer was hydrolyzed with 5% aqueous solution of sodium hydroxide at the refluxing temperature for 5 hours. After cooling, the aqueous layer was washed with ether. The aqueous layer was acidified by adding hydrochloric acid and extracted again with ether, which was followed by washing with water, drying with anhydrous magnesium sulfate, and filtration. Ether was then removed by reduced-pressure evaporation to obtain crude product. Finally, 23 g of α-(3-benzoylphenyl)propionic acid (ketoprofen) was obtained by re-crystallization from benzene/petroleum ether mixture. The melting point and spectrum were the same as those of an authentic sample.

Provenance & Evidence