反应详情

A mixture of 5-hydroxymethyl-thiophene-3-carboxylic acid (14.5 g, 91.7 mmol), concentrated H2SO4 (5.2 mL, 93.5 mmol) and methanol (250 mL) is heated to reflux for 3.5 h. After cooling, the mixture is poured into water and extracted with dichloromethane (3×). The combined extracts are washed successively with saturated aq NaCl, aq NaHCO3 and water followed by drying over Na2SO4, filtration and concentration in vacuo. The residue is purified by distillation to give 5-hydroxymethyl-thiophene-3-carboxylic acid methyl ester (8.8 g, 56%) as a clear oil: bp 155-157° C./6-7 mbar; 1H NMR (CDCl3, 300 MHz) δ 7.98 (s, 1 H), 7.35 (s, 1 H), 4.78 (s, 2 H), 3.80 (s, 3 H), 2.63 (s, 1 H).

1. temperatureis heated
2. temperatureto reflux for 3.5 h
3. temperatureAfter cooling
4. extractionextracted with dichloromethane (3×)
5. washThe combined extracts are washed successively with saturated aq NaCl, aq NaHCO3 and water
6. dry with materialby drying over Na2SO4, filtration and concentration in vacuo
7. distillationThe residue is purified by distillation