反应详情

A mixture of 4-bromo-thiophene-2-carbaldehyde (175 g, 916 mmol), ethylene glycol (71.1 g, 1.15 mol) and p-toluenesulfonic acid (0.19 g, 1.0 mmol) in toluene (250 mL) is heated to reflux for 7 h using a Dean-Stark apparatus. After cooling, the solution is washed with aq NaHCO3, dried over Na2SO4, filtered and concentrated in vacuo. The residue is distilled to give 2-(4-bromo-thiophen-2-yl)-[1,3]dioxolane (210.6 g, 98%) as a colorless liquid: bp 133-143/11-14 mBar; 1H NMR (CDCl3, 300 MHz) δ 7.21 (s, 1 H), 7.04 (s, 1 H), 6.04 (s, 1 H), 3.95-4.18 (m, 4 H).

1. temperatureis heated
2. temperatureto reflux for 7 h
3. temperatureAfter cooling
4. washthe solution is washed with aq NaHCO3
5. dry with materialdried over Na2SO4
6. filtrationfiltered
7. concentrationconcentrated in vacuo
8. distillationThe residue is distilled