Reaktion #55092

Reaktionsgleichung

chloroacetic acid

sodium hydroxide

piperonyl alcohol

thiouronium

HCl

thiourea

hydrobromic acid

diisopropyl ether

bicarbonate

→

said acid

Ausbeute 52.8%

3,4-Methylenedioxybenzylthio-acetic acid

Ausbeute 52.8%

Lösungsmittel

water

water

—

petroleum ether

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigeequipped with a magnetic stirrer and a condenser
2. 2
   TemperaturThe temperature is raised to 95° C.
3. 3
   Temperaturto cool
4. 4
   Filtrationthese are filtered off
5. 5
   SonstigeThe precipitate thus obtained
6. 6
   TemperaturThe mixture is heated to 70° C.
7. 7
   TemperaturThe whole is then heated
8. 8
   Temperaturunder reflux for half an hour
9. 9
   Temperaturafter which it is cooled
10. 10
    Sonstigethe precipitate obtained
11. 11
    workup.DISSOLUTIONis redissolved in
12. 12
    Waschenthe solution is washed with methylene chloride
13. 13
    Filtrationfiltered over charcoal
14. 14
    Sonstigeto precipitate 3,4-methylenedioxybenzylthio-acetic acid, which
15. 15
    Filtrationis filtered off
16. 16
    SonstigeAfter recrystallisation

Vorschrift

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.

Quelle