Hydrogen Bromide → 2-Bromo-4-chlorobenzothiazole

HRID 234702

Reaction equation

HRID 234702 reaction equation
N[C:2]1[S:3][C:4]2[CH:10]=[CH:9][CH:8]=[C:7]([Cl:11])[C:5]=2[N:6]=1.N([O-])=O.[Na+].[BrH:16]>O.[Cu]Br>[Br:16][C:2]1[S:3][C:4]2[CH:10]=[CH:9][CH:8]=[C:7]([Cl:11])[C:5]=2[N:6]=1

Participants

6

Reactant 3

HCID 260Hydrogen Bromide2×HCID 298722-Benzothiazolamine, 4-chloro-HCID 23668193Sodium Nitrite

Product 1

HCID 771782-Bromo-4-chlorobenzothiazole

Reagents, catalysts & solvents 2

HCID 24593copper(I) bromideCatalystHCID 962WaterSolvent3×

Conditions

Temperature
0 °C

Procedure

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.

Workup

  1. temperatureto reflux
  2. temperatureMaintain
  3. temperatureat reflux for 20 minutes
  4. temperaturemaintaining a temperature of 0° C
  5. additionadd by dropwise addition (while keeping cold) to
  6. stirringa rapidly stirring
  7. stirringStir at room temperature for 20 minutes
  8. temperatureheat on a steam bath for an additional 20 minutes
  9. waitAllow to stand overnight
  10. extractionextract into methylene chloride
  11. dry with materialdry (MgSO4)
  12. customEvaporate the solvent in vacuo
  13. custompurify by chromatography

Sources & evidence

ORD record
ord-1ad6f2159d8446daaf5438a39c67dd90
Source dataset
uspto-grants-1997_01
Patent number
US05596003

Linked notes

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