Hydrogen Bromide → 2-Bromo-4-chlorobenzothiazole

HRID 1736440Notes

Reaction equation

HRID 1736440 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 (0.255 mol) 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 (17.56 g, 0.255 mol) in water (90 mL), 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 (42.03 g, 0.293 mol) in 48% hydrobromic acid (86 mL) and water (225 mL). 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-56ec7399bb014e5dbc77fde72c229d51
Source dataset
uspto-grants-1996_07
Patent number
US05541200

Reaction notes

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