反应详情

13.07 g (0.172 mol) of thiourea and 86 ml of water are charged into a 1 liter three-necked flask equipped with a magnetic stirrer and a condenser. The mixture is heated to 50°-60° C. and 32 g (0.172 mol) of 3,4-dimethoxybenzyl chloride are added all at once. The mixture is heated under reflux and boiling is maintained for 15 minutes; the solution becomes limpid. Thereafter the solution is cooled and a solution of 27.52 g (0.688 mol) of NaOH in 43 ml of water is added dropwise at about 60° C. The mixture is again heated under reflux for 30 minutes, cooled and a solution of sodium chloroacetate (obtained by neutralising 22.76 g of chloroacetic acid in 172 ml of water with 20.23 g of NaHCO3) is added dropwise at 60°-70° C. Thereafter the whole is heated under reflux for 30 minutes, cooled and filtered and the filtrate then acidified with 3 N HCl. After recrystallisation from toluene, 28.7 g of 3,4-dimethoxybenzylthio-acetic acid are obtained. Yield: 69%. Instantaneous melting point=94° C.

1. customequipped with a magnetic stirrer and a condenser
2. temperatureThe mixture is heated to 50°-60° C.
3. temperatureThe mixture is heated
4. temperatureunder reflux
5. temperatureboiling is maintained for 15 minutes
6. temperatureThereafter the solution is cooled
7. temperatureThe mixture is again heated
8. temperatureunder reflux for 30 minutes
9. temperaturecooled
10. temperatureThereafter the whole is heated
11. temperatureunder reflux for 30 minutes
12. temperaturecooled
13. filtrationfiltered
14. customAfter recrystallisation from toluene, 28.7 g of 3,4-dimethoxybenzylthio-acetic acid
15. customare obtained