Hydrochloric Acid → 2,6-Dichloro-4-(trifluoromethyl)benzaldehyde

Temperature

-78 °C

1-Bromo-2,6-dichloro-4-trifluoromethylbenzene (80 g, 0.27 mol) was dissolved in anhydrous diethyl ether (480 ml) and the solution was cooled to -78° C. Butyllithium (2.5M solution in hexane, 100 ml) was added dropwise with stirring in an atmosphere of nitrogen while maintaining the temperature below -70° C. After stirring for a further 1 hour at -78° C. N-formylpiperidine (30.8 g, 0.27 mol) was added dropwise. The mixture was stirred at -78° C. overnight and allowed to warm slowly to 0° C. Hydrochloric acid (2M, 200 ml) was added dropwise to the solution with ice-cooling. The two layers were separated and the organic phase was washed with water, dried over anhydrous sodium sulphate and evaporated to dryness. The oily residue was dissolved in a mixture of ethyl acetate and petroleum spirit (b.p. 60°-80° C.) (1:10) and the solution was filtered through a column of silica. Evaporation of the filtrate and distillation of the resultant oil gave 2,6-dichloro-4-trifluoromethylbenzaldehyde (43.7 g) as a colourless liquid, b.p. 115° C. at 14 mmHg.

1. temperaturewhile maintaining the temperature below -70° C
2. stirringAfter stirring for a further 1 hour at -78° C
3. stirringThe mixture was stirred at -78° C. overnight
4. temperatureto warm slowly to 0° C
5. temperaturecooling
6. customThe two layers were separated
7. washthe organic phase was washed with water
8. dry with materialdried over anhydrous sodium sulphate
9. customevaporated to dryness
10. dissolutionThe oily residue was dissolved in a mixture of ethyl acetate and petroleum spirit (b.p. 60°-80° C.) (1:10)
11. filtrationthe solution was filtered through a column of silica
12. customEvaporation of the filtrate and distillation of the resultant oil

ORD record

ord-cfa3321012ff4b8da8abdeed996ac0f3

Source dataset

uspto-grants-1993_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05206257