Sodium Hydroxide → 5-Trifluoromethoxysalicylic acid

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반응 단계

To a stirring solution of NaOH (8.15 g, 203.8 mmol) in water (35 mL, 5.8 M) was added an aq solution of silver nitrate (17.3 g, 101.9 mmol, 35 mL water, 2.9 M). A brownish solid formed. The flask was placed in an ice bath and to the stirring suspension was added 2-hydroxy-5-trifluoromethoxy-benzaldehyde in 500 mg portions (10.0 g, 48.5 mmol). After addition was complete and the reaction was stirred for 10 min in an ice bath, the mixture was filtered and the brownish precipitate was washed with hot water. The combined washings were acidified with conc HCl to pH 1 and the precipitate was collected by vacuum filtration. This solid was then dissolved in ethyl acetate. The ethyl acetate was washed with saturated aq NaCl, dried over Na2SO4, and filtered. The aqueous layer was also extracted with ethyl acetate. This organic layer was washed with saturated aq NaCl, dried over Na2SO4, filtered and concentrated to provide 2-hydroxy-5-trifluoromethoxy-benzoic acid (9.8 g, 91%) as a white solid: Rf 0.38 (20% methanol in dichloromethane); 1H NMR (CDCl3, 300 MHz) δ 10.30 (bs, 1 H), 7.79 (d, J=3.0 Hz, 1 H), 7.41 (dd, J l=9.3 Hz, J2=3.0 Hz, 1 H), 7.05 (d, J=9.0 Hz, 1 H).

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