Reacción #321884

Ecuación de reacción

hydrobromic acid

hydrobromic acid

2-amino-4-chlorobenzothiazole

sodium nitrite

→

2-bromo-4-chlorobenzothiazole

Disolventes

water

water

water

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturato reflux
2. 2
   TemperaturaMaintain
3. 3
   Temperaturaat reflux for 20 minutes
4. 4
   Temperaturamaintaining a temperature of 0° C
5. 5
   workup.ADDITIONadd by dropwise addition (while keeping cold) to
6. 6
   workup.STIRRINGa rapidly stirring
7. 7
   workup.STIRRINGStir at room temperature for 20 minutes
8. 8
   Temperaturaheat on a steam bath for an additional 20 minutes
9. 9
   workup.WAITAllow to stand overnight
10. 10
    Extracciónextract into methylene chloride
11. 11
    Secadodry (MgSO4)
12. 12
    OtroEvaporate the solvent in vacuo
13. 13
    Otropurify by chromatography

Procedimiento

Slurry 2-amino-4-chlorobenzothiazole (0.255mol) in water (325 mL), heat to reflux and add 48% hydrobromic acid (130 mL). Maintain at reflux for 20 minutes, cool to 0° C. and add a solution of sodium nitrite (17.56g, 0.255mol) in water (90mL), maintaining a temperature of 0° C. Stir at 0° C. for 15 minutes and add by dropwise addition (while keeping cold) to a rapidly stirring mixture of copper (I) bromide (42.03g, 0.293mol) in 48% hydrobromic acid (86mL) and water (225mL). Stir at room temperature for 20 minutes and then heat on a steam bath for an additional 20 minutes. Allow to stand overnight, extract into methylene chloride and dry (MgSO4). Evaporate the solvent in vacuo and purify by chromatography to give 2-bromo-4-chlorobenzothiazole.

Fuente