Dimethyl Sulfate → Methyl 4-hydroxythiophene-2-carboxylate

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Reaction Steps

50.0 g (0.347 mol) of 4-hydroxy-2-thiophenecarboxylic acid and 58.3 g (0.694 mol) of sodium carbonate are heated to the boiling point in 990 ml of absolute 2-butanone under nitrogen, and 43.7 g (0.347 mol) of dimethyl sulfate are added dropwise in the course of 20 minutes. The mixture is heated under reflux for a further 2.5 hours. It is then evaporated in vacuo and the residue is partitioned between saturated sodium carbonate solution and ether. The aqueous phase is extracted five more times with 80 ml of ether each time. The combined organic phases are dried over sodium sulfate/active charcoal, filtered and evaporated.

Provenance & Evidence