Carbon Dioxide → 2,4,5-Trifluoro-3-(trifluoromethyl)benzoic acid

Participants

Reaction Conditions

Reaction Steps

A solution of n-butyl lithium (2.6M in hexanes, 9.6 ml, 25 mmol) was added dropwise through an addition funnel over 15 minutes to a solution of 1-bromo-2,4,5-trifluoro-3-(trifluoromethyl)benzene (7.00 g, 25 mmol) in ether (100 ml) stirred under N2 at -78° C. After 5 minutes the mixture was rapidly blown by catheter onto a suspension of dry ice (100 g) in ether (100 ml). After 5 minutes TFA (2 ml) was added to this. When the solution had warmed up to 20° C., it was washed with diluted HCl (0.5M, 20 ml), and extracted with dilute base (0.5N, 2×50 ml). The combined basic extracts were washed with ether (25 ml), made acidic with concentrated HCl (~4 ml), and extracted with ether (3×50 ml). The combined ethereal extracts were washed with water (50 ml), saturated brine (50 ml), and dried (MgSO 4). The solvent was removed under reduced pressure to give 2,4,5-trifluoro-3-(trifluoromethyl)benzoic acid (4.21 g, 69%) as white microscopic needles; mp 87°-90° C. Nmr (CDC3) δ 11.80 (1H, br s, OH), 8.05 (1H, d of t, Jd =6 Hz, aromatic).

Provenance & Evidence