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

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Reaction Conditions

Reaction Steps

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.

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