反应详情

Malonic acid (22.2 g, 0.213 mol) and menthol (70 g, 0.448 mol) are brought to reflux for 6 hours in 100 ml of toluene in the presence of 2 ml of concentrated sulfuric acid in a reactor surmounted by a Dean & Stark apparatus. The water formed is removed by azeotropic distillation. The organic phase is washed 3 times with water and is dried over sodium sulfate. The excess menthol is removed by distillation under vacuum (140° C. under 0.6 hPa). The residue is treated with animal charcoal in isopropanol at reflux. After filtering, rinsing and evaporating the solvent, 61.8 g (Yield 76%) of dimenthyl malonate are obtained in the form of a yellow oil which is used as is in the following stage.

1. customis removed by azeotropic distillation
2. washThe organic phase is washed 3 times with water
3. dry with materialis dried over sodium sulfate
4. customThe excess menthol is removed by distillation under vacuum (140° C. under 0.6 hPa)
5. additionThe residue is treated with animal charcoal in isopropanol
6. temperatureat reflux
7. filtrationAfter filtering
8. washrinsing