Acetic Acid → 2,6-Difluorobenzyl alcohol

Participants

Reaction Steps

A stirred solution of 25.0 g (0.158 mole) of 2,6-difluorobenzoic acid in 300 ml of diethyl ether was purged with nitrogen, and 20 ml of a 1 molar solution of borane in tetrahydrofuran was carefully added dropwise. The addition caused the reaction mixture to effervesce. When vigorous effervescence subsided, the reaction mixture was heated to reflux and an additional 170 ml of a 1 molar solution of borane (0.190 mole total) in tetrahydrofuran was added dropwise at a rate just sufficient to promote gentle reflux. Upon complete addition the reaction mixture was heated under reflux for an additional 1 hour, allowed to cool to ambient temperature and stand for 16 hours, then heated under reflux again for 1 hour. Acetic acid (11 ml, 0.19 mole) was added, then the reaction mixture was cooled in an ice-water bath and 100 ml of a saturated aqueous solution of ammonium chloride was added slowly. Upon complete addition the reaction mixture was stirred for 0.5 hour, then concentrated under reduced pressure to give a pasty residue. Diethyl ether was added and the mixture was washed with three portions of water, two portions of aqueous 10% sodium carbonate, two portions of water, and one portion of a saturated aqueous solution of sodium chloride. The organic layer was dried with magnesium sulfate, filtered, and the filtrate concentrated under reduced pressure to give 18.9 g of (2,6-difluorophenyl)methanol as a yellow oil. The nmr spectrum was consistent with the proposed structure.

Provenance & Evidence