反应详情

温度

60 °C

A solution of 18.24 g (0.24 mol) of thiourea in 104 ml of 48% strength hydrobromic acid and 20 ml of water is introduced into a one liter three-necked flask equipped with a magnetic stirrer and a condenser. The mixture is heated to 60° C. and 30.4 g (0.2 mol) of piperonyl alcohol are introduced. The temperature is raised to 95° C. and the mixture is left to cool. Crystals of the thiouronium salt appear; these are filtered off and dried. The precipitate thus obtained is introduced into a 500 ml three-necked flask with 60 ml of sodium hydroxide solution. The mixture is heated to 70° C. and 15.6 g (0.164 mol) of chloroacetic acid in 30 ml of water are added dropwise. Thereafter the whole is heated under reflux for half an hour and then cooled. The mixture is acidified with 3 N HCl, the precipitate obtained is redissolved in a dilute bicarbonate solution, and the solution is washed with methylene chloride, filtered over charcoal and acidified once more with 3 N HCl in order to precipitate 3,4-methylenedioxybenzylthio-acetic acid, which is filtered off. After recrystallisation from a diisopropyl ether/petroleum ether mixture (1:1 v/v), 18.2 g (yield 40%) of the said acid are collected (instantaneous melting point=87° C.).

1. customequipped with a magnetic stirrer and a condenser
2. temperatureThe temperature is raised to 95° C.
3. waitthe mixture is left
4. temperatureto cool
5. filtrationthese are filtered off
6. customdried
7. customThe precipitate thus obtained
8. temperatureThe mixture is heated to 70° C.
9. temperatureThereafter the whole is heated
10. temperatureunder reflux for half an hour
11. temperaturecooled
12. customthe precipitate obtained
13. washthe solution is washed with methylene chloride
14. filtrationfiltered over charcoal
15. customto precipitate 3,4-methylenedioxybenzylthio-acetic acid, which
16. filtrationis filtered off