Réaction #2075740

Équation de réaction

HBr

2-Amino-3-nitrophenol

hydrobromic acid

sodium nitrite

→

2-bromo-3-nitrophenol

Rendement 45.0%

Solvants

H2O

1,4-dioxane

H2O

H2O

Conditions de réaction

Traitement

1. 1
   TempératureThe mixture was heated
2. 2
   Températureto reflux
3. 3
   workup.ADDITIONUpon completion of the addition
4. 4
   Températurethe reflux was maintained an additional 15 min
5. 5
   workup.ADDITIONwas added over a period of 30 min
6. 6
   Autrethe mixture was transferred to a jacketed dropping funnel
7. 7
   Températurewarmed to 60° C.
8. 8
   workup.STIRRINGstirred for an additional 15 min
9. 9
   Températurecooled to room temperature
10. 10
    workup.WAITleft
11. 11
    workup.STIRRINGto stir overnight
12. 12
    AutreThe reaction mixture was transferred to a separatory funnel
13. 13
    Extractionextracted with ether (3×150 mL)
14. 14
    Lavagewashed with brine (1×)
15. 15
    Séchagedried (Na2SO4)
16. 16
    Filtrationfiltered
17. 17
    Concentrationconcentrated
18. 18
    Autreto afford the crude product (7.99 g) as a red-brown oil
19. 19
    AutreThe crude material was purified by flash column chromatography (1:25 ultra pure silica gel, 230-400 mesh, 40-60 mm, 60 angstroms

Mode opératoire

2-Amino-3-nitrophenol B1 (5 g; 32.4 mmol) was dissolved in H2O (29.5 mL) and 1,4-dioxane (14.7 mL). The mixture was heated to reflux and hydrobromic acid (48%; 16.7 mL; 147 mmol) was added dropwise over a period of 20 min. Upon completion of the addition, the reflux was maintained an additional 15 min. The reaction was cooled to 0° C. (ice bath), and sodium nitrite (2.23 g; 32.3 mmol) in H2O (20 mL) was added over a period of 30 min. The stirring was continued for 15 min at 0° C., then the mixture was transferred to a jacketed dropping funnel (0° C.) and added dropwise to a stirred mixture of Cu(I)Br (5.34 g; 37.2 mmol) in H2O (29.5 mL) and HBr (48%; 16.7 mL; 147 mmol) at 0° C. The reaction was stirred for 15 min at 0° C., warmed to 60° C., stirred for an additional 15 min, cooled to room temperature, and left to stir overnight. The reaction mixture was transferred to a separatory funnel and extracted with ether (3×150 mL). The organic layers were combined, washed with brine (1×), dried (Na2SO4), filtered and concentrated to afford the crude product (7.99 g) as a red-brown oil. The crude material was purified by flash column chromatography (1:25 ultra pure silica gel, 230-400 mesh, 40-60 mm, 60 angstroms; CH2Cl2 as the solvent) to afford pure 2-bromo-3-nitrophenol B2 (45%; 3.16 g) as an orange-brown solid.

Source