Yield:950525-96-9 73%

Reaction Conditions:

with sulfuric acid at 130; for 0.166667 h;

Steps:

142

3-chloro-4-fluoro-5-hydroxybenzoic acid; A solution of 3-chloro-2-fluoro-5-(trifluoromethyl)phenol (5g, 23 mmol) in cone H₂SO₄ (15ml_) was heated by microwave to 130C for lOminutes. (Caution: Reaction develops pressure. Vent carefully before opening.) The resulting dark mixture was dropped into water and the resulting purple solids collected by filtration, rinsed with water and air dried to give 3-chloro-4-fluoro-5-hydroxybenzoic acid in73% yield. 1H NMR (400 MHz, DMSO-Cf₆) δ ppm 13.25 (br. s., 1 H), 10.83 (s, 1 H), 7.29 - 7.69 (m, 2 H)

References:

WO2007/105058,2007,A2 Location in patent:Page/Page column 73