Dimethyl Sulfate → 3-Methoxythiophene-2-carboxylic acid

Participants

Reaction Steps

48.5 g (0.31 mmoles) of 3-hydroxy-2-thiophene carboxylic acid methyl ester (IV: R3 =H) are dissolved in 400 ml of acetone, 84.7 g (0.61 moles) of potassium carbonate, 77.3 g (0.61 moles) of dimethylsulfate are added, and the mixture is refluxed with stirring for 1 hour. The salt mass is aspirated, washed several times with acetone and the combined filtrate is concentrated in vacuo. 750 ml of aqueous 2N sodium hydroxide are added and boiled. The reaction solution is cooled, washed with ether and acidified with concentrated HCl. The precipitating colorless crystals are aspirated and recrystallized from ethanol. Yield: 43.1 g (89%), m.p. 184°-185° C.

Provenance & Evidence