Réaction #55092

Équation de réaction

chloroacetic acid

sodium hydroxide

piperonyl alcohol

thiouronium

HCl

thiourea

hydrobromic acid

diisopropyl ether

bicarbonate

→

said acid

Rendement 52.8%

3,4-Methylenedioxybenzylthio-acetic acid

Rendement 52.8%

Solvants

water

water

—

petroleum ether

Conditions de réaction

Traitement

1. 1
   Autreequipped with a magnetic stirrer and a condenser
2. 2
   TempératureThe temperature is raised to 95° C.
3. 3
   Températureto cool
4. 4
   Filtrationthese are filtered off
5. 5
   AutreThe precipitate thus obtained
6. 6
   TempératureThe mixture is heated to 70° C.
7. 7
   TempératureThe whole is then heated
8. 8
   Températureunder reflux for half an hour
9. 9
   Températureafter which it is cooled
10. 10
    Autrethe precipitate obtained
11. 11
    workup.DISSOLUTIONis redissolved in
12. 12
    Lavagethe solution is washed with methylene chloride
13. 13
    Filtrationfiltered over charcoal
14. 14
    Autreto precipitate 3,4-methylenedioxybenzylthio-acetic acid, which
15. 15
    Filtrationis filtered off
16. 16
    AutreAfter recrystallisation

Mode opératoire

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.

Source