Dimethyl Sulfoxide → 3,5-dichloro-4-formylbenzoic acid

Participants

Reaction Conditions

Reaction Steps

In a 1 liter 4-necked round-bottomed flask were place 300 ml of methylene chloride and cooled down to -78° C. 26.0 g (0.20 mole) of oxalyl chloride were added slowly, followed by dropwise addition of 35.4 g (0.452 mole) of dry dimethylsulfoxide in 25 ml of methylene chloride, keeping the temperature below -70° C. After the addition was completed the reaction mixture was stirred at -78° C. for 30 minutes and 50.0 g (0.226 mole) of 4-hydroxymethyl-3,5-dichlorobenzoic acid were added in 1 portion 82.5 g (0.817 mole) of triethylamine in 25 ml of methylene chloride were added dropwise, keeping the temperature below -65° C. The reaction mixture was warmed up slowly to room temperature and stirred during 90 minutes, washed with 2% aqueous sodium hydroxide (3×300 ml). The combined basic layers were washed with hexane (2×250 ml) then acidified with concentrated hydrochloric acid and then extracted with ethyl acetate (4×200 ml). The combined organic layers were washed with water (1×500 ml), and then with brine (1×300 ml) and dried over anhydrous magnesium sulfate. The solvent was then eliminated in a rotavap. The resulted oily product was triturated with hexane and filtered yielding 39.6 g (80% purity) 4-formyl-3,5-dichloro benzoic acid as a tan solid.

Provenance & Evidence