Reaktion #412944

Reaktionsgleichung

water methanol

4-bromo-2-aminothiophenol hydrochloride

p-bromobenzoic acid

→

2-(4-bromophenyl)-5-bromobenzothiazole

Lösungsmittel

sulfolane

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONTo this mixture was added a solution
2. 2
   TemperaturThe reaction mixture was slowly heated to 200° C.
3. 3
   Temperaturmaintained at that temperature for 1 hour
4. 4
   TemperaturAfter cooling
5. 5
   Sonstigeto precipitate the product
6. 6
   FiltrationThe light tan precipitate was filtered
7. 7
   Waschenwashed with dilute ammonium hydroxide
8. 8
   Waschenwashed with water
9. 9
   Sonstigeair dried
10. 10
    SonstigeThe 2-(4-bromophenyl)-5-bromobenzothiazole was recrystallized from toluene
11. 11
    Sonstigeto give 24.5 g (80% of theoretical), m.p. 162°-163° C.

Vorschrift

A mixture of 20 g (0.083 mole) of 4-bromo-2-aminothiophenol hydrochloride and 270 g of deoxygenated polyphosphoric acid was heated at 70° C. for 4 hours. To this mixture was added a solution containing 22 g (0.11 mole) of p-bromobenzoic acid dissolved in 109 g of sulfolane. The reaction mixture was slowly heated to 200° C. and maintained at that temperature for 1 hour. After cooling, the reaction mixture was poured into a 1:1 water-methanol solution to precipitate the product. The light tan precipitate was filtered, washed with dilute ammonium hydroxide, washed with water, and then air dried. The 2-(4-bromophenyl)-5-bromobenzothiazole was recrystallized from toluene to give 24.5 g (80% of theoretical), m.p. 162°-163° C.

Quelle