反应详情

温度

0 °C

To a 1 L flask were added finely powdered p-bromoaniline (69 g, 0.4 mol), water (200 mL) and conc. HCl (100 mL, 1.2 mol). The mixture was cooled in an ice bath to less than 5° C. A solution of sodium nitrite (30 g, 0.43 mol) in water (90 mL) was added dropwise to the aniline suspension over approx. 1 h, while maintaining the temperature at less than 5° C. The mixture was stirred for a further 30 min and then was gravity filtered through a No. 1 paper into a chilled flask. The solution was added in small portions to a solution of 92% ammonium sulfite (118 g, 0.8 mol) in water (250 mL), which had been chilled to 0° C., at a rate such that the temperature remained at less than 5° C. (approx. 1 h). During the addition a yellow solid formed in the mixture. After the addition was completed, stirring was continued for 1 h at 0° C. and the mixture was then allowed to warm to rt. The solid was filtered off and the filtrate was treated with conc. HCl (120 mL). The solution was heated to reflux during which time a solid formed and then mostly dissolved. The hot solution was filtered and then allowed to cool to rt before chilling in a refrigerator overnight. The crystals were filtered off and were washed with 1 M HCl (60 mL). The solid was added to a mixture of DCM (1 L) and 1N sodium hydroxide (600 mL) and the suspension was shaken until the solid dissolved. The layers were separated and the aqueous phase was washed again with DCM (2×400 mL). The combined organic solutions were dried (MgSO4), filtered and the solvent was evaporated in vacuo to afford p-bromophenylhydrazine (50.3 g, 67%).

1. temperatureThe mixture was cooled in an ice bath to less than 5° C
2. temperaturewhile maintaining the temperature at less than 5° C
3. filtrationfiltered through a No
4. customremained at less than 5° C.
5. custom(approx. 1 h)
6. additionDuring the addition a yellow solid
7. customformed in the mixture
8. additionAfter the addition
9. stirringstirring
10. waitwas continued for 1 h at 0° C.
11. temperatureto warm to rt
12. filtrationThe solid was filtered off
13. additionthe filtrate was treated with conc. HCl (120 mL)
14. temperatureThe solution was heated
15. temperatureto reflux during which time a solid
16. customformed
17. dissolutionmostly dissolved
18. filtrationThe hot solution was filtered
19. temperatureto cool to rt
20. temperaturebefore chilling in a refrigerator overnight
21. filtrationThe crystals were filtered off
22. washwere washed with 1 M HCl (60 mL)
23. additionThe solid was added to a mixture of DCM (1 L) and 1N sodium hydroxide (600 mL)
24. stirringthe suspension was shaken until the solid
25. dissolutiondissolved
26. customThe layers were separated
27. washthe aqueous phase was washed again with DCM (2×400 mL)
28. dry with materialThe combined organic solutions were dried (MgSO4)
29. filtrationfiltered
30. customthe solvent was evaporated in vacuo