Reacción #55092

Ecuación de reacción

chloroacetic acid

sodium hydroxide

piperonyl alcohol

thiouronium

HCl

thiourea

hydrobromic acid

diisopropyl ether

bicarbonate

→

said acid

Rendimiento 52.8%

3,4-Methylenedioxybenzylthio-acetic acid

Rendimiento 52.8%

Disolventes

water

water

—

petroleum ether

Condiciones de reacción

Tratamiento posterior

1. 1
   Otroequipped with a magnetic stirrer and a condenser
2. 2
   TemperaturaThe temperature is raised to 95° C.
3. 3
   Temperaturato cool
4. 4
   Filtraciónthese are filtered off
5. 5
   OtroThe precipitate thus obtained
6. 6
   TemperaturaThe mixture is heated to 70° C.
7. 7
   TemperaturaThe whole is then heated
8. 8
   Temperaturaunder reflux for half an hour
9. 9
   Temperaturaafter which it is cooled
10. 10
    Otrothe precipitate obtained
11. 11
    workup.DISSOLUTIONis redissolved in
12. 12
    Lavadothe solution is washed with methylene chloride
13. 13
    Filtraciónfiltered over charcoal
14. 14
    Otroto precipitate 3,4-methylenedioxybenzylthio-acetic acid, which
15. 15
    Filtraciónis filtered off
16. 16
    OtroAfter recrystallisation

Procedimiento

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 allowed to cool. Crystals of thiouronium salt appear; these are filtered off and suction-drained. The precipitate thus obtained is introduced into a 500 ml three-necked flask together 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. The whole is then heated under reflux for half an hour, after which it is cooled. The mixture is acidified with 3 N HCl, the precipitate obtained is redissolved in a dilute (sodium) bicarbonate solution, and the solution is washed with methylene chloride, filtered over charcoal and again acidified with 3 N HCl so as to precipitate 3,4-methylenedioxybenzylthio-acetic acid, which is filtered off. After recrystallisation from a 1:1 (volume/volume) mixture of diisopropyl ether and petroleum ether, 18.2 g (40% yield) of the said acid (instantaneous melting point=87° C.) are collected.

Fuente