反应详情

温度

80 °C

A 500 mL flask equipped with mechanical stirrer, condenser, addition funnel, and thermometer was charged with 50.0 g (0.255 mol) of 2-nitrobenzene sulfonyl chloride (Aldrich). Upon dropwise addition of 5M aqueous sodium hydroxide (125 mL, 0.625 mol) the reaction mixture warmed to 80° C. and a dark red/brown solution resulted. The mixture was stirred for 1 hour and the flask allowed to cool to room temperature. Next, 52.5 g of zinc dust (0.803 mol, Mallinckrodt) was added in one portion. The reaction mixture turned green and warmed to 40° C. Sodium hydroxide (50 percent w/w, 113.75 g, 1.42 mol) was then cautiously added dropwise. The temperature of the reaction mixture rose quickly and vigorous reflux ensued. The reaction mixture turned black, then light green, and finally gray. After addition was complete, the reaction mixture was heated to 90° C. and stirred for 30 minutes. The reaction mixture was cooled and filtered through diatomaceous earth. The zinc salts were washed several times with water yielding 850 mL of an orange/brown filtrate. The filtrate was immediately transferred to a 2 L flask equipped with mechanical stirrer, condenser, addition funnel, nitrogen inlet, and thermometer. Concentrated hydrochloric acid (250 mL) was added dropwise. A light yellow precipitate formed, leaving a clear yellow supernatant (pH=7). Further addition of acid caused the solid to dissolve and the solution to turn orange and then brown (pH=4). More acid caused a tan precipitate to form and persist. After HCl addition was complete, the temperature had risen to 45° C. and the pH was 1. The reaction mixture was stirred for an additional hour and then cooled in an ice bath. The precipitate was collected by filtration and dried in a vacuum oven at ambient temperature yielding a cake which weighed 11.69 g. The product was purified by dissolving it in 150 mL of hot water containing 13.5 mL of 5M sodium hydroxide. Concentrated HCl (15 mL) was then slowly added to reprecipitate the product. Vacuum filtration and drying in a vacuum oven at ambient temperature yielded 11.07 g (28.6 percent) of 4,4'-diaminobiphenyl-3,3'-disulfonic acid.

1. customA 500 mL flask equipped with mechanical stirrer, condenser, addition funnel
2. customa dark red/brown solution resulted
3. temperatureto cool to room temperature
4. temperaturewarmed to 40° C
5. temperaturevigorous reflux
6. additionAfter addition
7. temperaturethe reaction mixture was heated to 90° C.
8. stirringstirred for 30 minutes
9. temperatureThe reaction mixture was cooled
10. filtrationfiltered through diatomaceous earth
11. washThe zinc salts were washed several times with water yielding 850 mL of an orange/brown filtrate
12. customThe filtrate was immediately transferred to a 2 L flask
13. customequipped with mechanical stirrer, condenser, addition funnel, nitrogen inlet
14. additionConcentrated hydrochloric acid (250 mL) was added dropwise
15. customA light yellow precipitate formed
16. customleaving a clear yellow supernatant (pH=7)
17. additionFurther addition of acid
18. dissolutionto dissolve
19. customto form
20. customhad risen to 45° C.
21. stirringThe reaction mixture was stirred for an additional hour
22. temperaturecooled in an ice bath
23. filtrationThe precipitate was collected by filtration
24. customdried in a vacuum oven at ambient temperature
25. customyielding a cake which
26. customThe product was purified
27. dissolutionby dissolving it in 150 mL of hot water containing 13.5 mL of 5M sodium hydroxide
28. additionConcentrated HCl (15 mL) was then slowly added
29. filtrationVacuum filtration
30. customdrying in a vacuum oven at ambient temperature