Dimethyl Sulfoxide → 3-Chloro-5-forMylbenzoic Acid

Participants

Reaction Conditions

Reaction Steps

In a 2 liter 4-necked round-bottomed flask were placed 500 ml of methylene chloride and cooled down to -78° C. 44.6 g (0.35 mole) of oxalyl chloride were added slowly, followed by dropwise addition of 57.7 g (0.74 mole) of dry dimethylsulfoxide in 40 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 71.5 g (0.38 mole) of the previously prepared 3-chloro-5-hydroxymethylbenzoic acid were added in 1 portion and 60 ml more of methylene chloride followed by dropwise addition of 149.5 g (1.48 mole) of triethylamine, keeping the temperature below -65° C. The reaction mixture was then warmed up slowly to room temperature and stirred during 90 minutes and washed with 2% aqueous sodium hydroxide (4×500 ml). The combined basic layers were washed with hexane once, then acidified with concentrated hydrochloric acid and then extracted with ethyl acetate (4×500 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, yielding 52 g of 3-formyl-5-chlorobenzoic acid.

Provenance & Evidence