Reacción #56457

Ecuación de reacción

HCl

sodium chloroacetate

thiourea

NaOH

p-fluorobenzylchloride

→

said acid

Rendimiento 90.6%

p-Fluorobenzylthioacetic acid

Rendimiento 90.6%

Disolventes

methylene chloride

water

cyclohexane

water

Condiciones de reacción

Tratamiento posterior

1. 1
   Otroequipped with a magnetic stirrer, a condenser
2. 2
   TemperaturaThe mixture is heated
3. 3
   Temperaturato reflux
4. 4
   Temperaturaboiling is maintained for about 15 minutes
5. 5
   TemperaturaThereafter the mixture is cooled
6. 6
   TemperaturaThe whole is heated
7. 7
   Temperaturaunder reflux for about 30 minutes
8. 8
   Temperaturacooled
9. 9
   TemperaturaThereafter the whole is heated
10. 10
    Temperaturaunder reflux for 30 minutes
11. 11
    Temperaturacooled
12. 12
    Otrothe oil obtained
13. 13
    Lavadothe solution is washed with a dilute solution of sodium bicarbonate
14. 14
    Filtraciónfiltered over charcoal
15. 15
    Otrothus precipitates
16. 16
    Filtraciónis filtered off

Procedimiento

A solution of 15.2 g (0.2 mol) of thiourea in 100 ml of water is introduced into a 1 liter 3-necked flask equipped with a magnetic stirrer, a condenser and dropping funnel, and 28.9 g (0.2 mol) of p-fluorobenzylchloride are introduced, at 50°-60° C., in a single operation. The mixture is heated to reflux and boiling is maintained for about 15 minutes; the solution becomes limpid. Thereafter the mixture is cooled and a solution of 32 g (0.8 mol) of NaOH in water is added dropwise at about 60° C. The whole is heated under reflux for about 30 minutes and cooled and a solution of about 0.28 mol of sodium chloroacetate (obtained by neutralising 26.46 g of chloroacetic acid in 200 ml of water with 23.52 g of sodium bicarbonate) is added dropwise at 60°-70° C. Thereafter the whole is heated under reflux for 30 minutes, and then cooled. The mixture is acidified with 3N HCl, the oil obtained is taken up in methylene chloride, the solution is washed with a dilute solution of sodium bicarbonate, filtered over charcoal and acidified once more with 3 N HCl and p-flourobenzylthioacetic acid thus precipitates and is filtered off. After recrystallisation from cyclohexane, 33.4 g (yield: 83%) of the said acid are collected. Instantaneous melting point: 68°-69° C.

Fuente