Potassium Hydroxide → 3-Chloro-5-(methoxycarbonyl)benzoic acid

Participants

Reaction Steps

In a 5 liter 3-necked round-bottomed flask were placed 5-chloroisophthalic acid dimethyl ester (146.4 g) and methanol (2.5 liters). To the resulting solution was added (dropwise) a solution of potassium hydroxide (42.8 g) in methanol (500 ml) with vigourous stirring under nitrogen. The resulting mixture was refluxed 2 hours, cooled down and the solvent was then eliminated in the rotavap. The residue was taken up in water (800 ml), the pH brought to 8 and the resulting solution washed with ethyl ether. The aqueous solution was made acidic with aqueous hydrochloric acid and extracted with ethyl acetate (3×400 ml). The combined organic layers were dried (magnesium sulfate) and the solvent was then eliminated in the rotavap. The solid residue was stirred in 1.3 liters of chloroform overnight and filtered. The solvent was then evaporated yielding 5-chloroisophthalic acid monomethyl ester as a white solid (29 g).

Provenance & Evidence