Example 2: Preparation of 4-chloro-2-(trifluoroacetyl)aniline hydrochloride hydrate
1. N-(4-chlorophenyl)-2,2-dimethylpropionamide (36.7 kg, 173 mol) was added to a solution of TMEDA (20.2 kg, 174 mol) in anhydrous tert-butyl methyl ether (271.5 kg), and cooled to -20°C.
2. a hexane solution (101.9 kg, 393 mol) of 2.7 N n-butyllithium was slowly added to the cooled slurry, keeping the reaction temperature below 5°C.
3. aging the reaction mixture at 0 to 5 °C for 2 hours, followed by cooling to below -15 °C.
4. ethyl trifluoroacetate (34.5 kg, 243 mol) was added rapidly to the reaction mixture.
5. After 30 minutes of reaction, the resulting solution was quenched by rapid pouring into 3 N HCl (196 L, 589 mol), controlling the temperature below 25°C.
6. The aqueous phase was separated and discarded, and the organic phase was concentrated by distillation to about 200 L solvent volume.
7. Acetic acid (352 kg) was added while about 325 kg of solvent was removed by distillation under vacuum at 100 mm Hg.
8. After cooling the solution to 30 °C, 12 N HCl (43.4 kg, 434 mol) was added and the mixture was heated to 65 to 70 °C and held for 4 hours.
9. The reaction slurry was cooled to 5 °C, the product was collected by filtration and washed with ethyl acetate (50.5 kg).
10. Vacuum drying gave 42.1 kg (87% yield) of 4-chloro-2-(trifluoroacetyl)aniline hydrochloride hydrate as a white crystalline solid.
Product characterization: melting point 159-162 °C (decomposition); 1H NMR (300 MHz, DMSO-d6) δ 7.65-7.50 (m, 2H), 7.10 (d, J = 8 Hz, 1H), 7.00 (br s, 3H); 19F NMR (282 MHz, DMSO-d6) δ -69.5.
