Bromide ion → 1-(3,5-Bis(trifluoromethyl)phenyl)ethan-1-one

Participants

Reaction Steps

A solution of 3,5-Bis(trifluoromethyl)bromobenzene (29.3 g) in 30 mL of THF was added to a mixture of magnesium granules (5.10 g) in THF (200 mL) heated at reflux (the reaction was initiated with approximately 5 mL of the bromide solution; the remainder was added slowly over 1 h). The mixture was aged for 30 min at reflux, cooled to RT and added over 1 h to a solution of acetic anhydride (40 mL) in THF (40 mL) maintained at −15° C. The resulting dark brown mixture was warmed to 10° C. in a water bath, and water (300 mL) was added. The pH of the vigorously stirred biphasic mixture was adjusted to 8.0 using 50% NaOH. MTBE (300 mL) was added, the layers were separated and the aqueous layer was further extracted with MTBE (3×150 mL). The organic layers were combined and concentrated in vacuo (bath at 30-35° C.; 50-80 torr). The concentrate was then distilled at atmospheric pressure to provide the pure product (20.7 g; 82% yield) with a boiling point of 187-189° C.

Provenance & Evidence