Peracetic Acid → Ibuprofen, (+-)-

Participants

Reaction Steps

To a stirred solution of 10.0 g (52.6 mmol) of 2-(4-isobutylphenyl)propionaldehyde (ibuprofen aldehyde)in n-butyl acetate (53 mL) cooled in a wet-ice bath (ca. 2° C.) was added 6.5 g (52.6 mmol) of 2,6-dimethylpyridine N-oxide (2,6-lutidine N-oxide). To this solution was then added slowly dropwise 29 mL (78.8 mmol) of a 20.0 weight percent solution of peracetic acid in ethyl acetate, at a rate slow enough such that the reaction temperature did not exceed 10° C. (ca. 25 minutes). After the initial exotherm, the temperature returned to 2° C., and the reaction was maintained at this temperature for an additional 4 hours. The cold reaction solution was then transferred into a separatory funnel, was diluted with n-butyl acetate (100 mL), and was washed with a 1% aqueous solution of sodium thiosulfate (Na2S2 O3, 100 mL). The butyl acetate layer was further washed with two portions of water (100 mL each), and the combined water washes were back-extracted with n-butyl acetate (100 mL). The combined butyl acetate layers were extracted with two portions of a 5% aqueous solution of sodium hydroxide (NaOH, 100 mL each). The combined NaOH solutions were acidified to pH=1 with a 10% aqueous solution of hydrochloric acid. The resulting solution was extracted with two portions of dichloromethane (100 mL each), and the extract was dried over anhydrous Na2SO4. The extract was filtered and concentrated in vacuo to give 10.3 g (94.6%) of ibuprofen as an off-white solid.

Provenance & Evidence