1918-79-2

13679-74-8

1918-79-2

GENERAL PROCEDURE: The general procedure for the synthesis of 5-methyl-2-thiophenecarboxylic acid from 2-acetyl-5-methylthiophene was as follows: Oxone (2 eq.) and trifluoroacetic acid (TFA, 2 eq.) were added to a solution of 2-acetyl-5-methylthiophene (100 mg, 1 eq.) in dioxane (5 mL). The reaction mixture was heated to reflux for 10 hours and subsequently cooled to room temperature. Water (10 mL) was added and the mixture was extracted with ethyl acetate (EtOAc, 2 x 20 mL). The organic layers were combined and washed with saturated sodium bicarbonate (NaHCO3) solution. The sodium bicarbonate solution and the aqueous layer were poured onto crushed ice and acidified with 2 M hydrochloric acid (HCl), at which point a colorless solid precipitated. The precipitate was collected by filtration, dried under vacuum and purified by column chromatography (silica gel; ethyl acetate-hexane, 1:9) to give 5-methyl-2-thiophenecarboxylic acid as a white crystalline solid. Yield: 0.096 g (95% based on 2-acetyl-5-methylthiophene); melting point: 122-123 °C.