Methane → 2-Amino-5-isopropyl-thiophene-3-carboxylic acid

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Reaction Steps

Methyl 2-amino-5-isopropylthiophene-3-carboxylate (59.8 g, 0.3 mol) was dissolved in 210 ml of 50% aqueous ethanol containing 24.6 g (0.6 mol) of sodium hydroxide and refluxed overnight. The ethanol was evaporated in vacuo, and the aqueous solution was extracted twice with chloroform. The aqueous phase was acidified by adjusting the pH to 4.5 with hydrochloric acid. The precipitate was isolated, dissolved in 150 ml of ethanol, and treated with 4 g of charcoal (Norit SU18). The mixture was filtered and concentrated to 100 ml. Water (500 ml) was added and the precipitate was filtered off to yield 39 g (70%) of 2-amino-5-isopropylthiophene-3-carboxylic acid melting with decomposition at 115° C. 1H-NMR (CDCl3, δ) : 1.2 (d, 6H), 2.9 (m, 1H), 5.8 (broad, 2H), 6.65 (s, 1H).

Provenance & Evidence