反应详情

25 g (0.13 mol) of (E)4-hydroxy-3-methoxycinnamic acid were dissolved in 180 ml of methanol, and 5 ml of concentrated sulfuric acid were added. The solution was heated under reflux for 2 hours. The main amount of the methanol (about 150 ml) was then distilled off and the residue that remained was poured into 500 ml of ice-water. The precipitated ester was filtered off with suction, washed in succession with cold water, with a small amount of a cold saturated sodium bicarbonate solution and again with cold water and dried at 50° C. under a water-jet vacuum. Chromatography on 250 g of silica gel using dichloromethane:diethyl ether (19:1) yielded 21.78 g of (E)4-hydroxy-3-methoxycinnamic acid methyl ester in the form of a light-yellow oil.

1. temperatureThe solution was heated
2. temperatureunder reflux for 2 hours
3. distillationThe main amount of the methanol (about 150 ml) was then distilled off
4. additionthe residue that remained was poured into 500 ml of ice-water
5. filtrationThe precipitated ester was filtered off with suction
6. washwashed in succession with cold water, with a small amount of a cold saturated sodium bicarbonate solution and again with cold water
7. customdried at 50° C. under a water-jet vacuum