Réaction #698628

Équation de réaction

sodium acetate

sodium hydroxide

sodium nitrite

2-aminobenzothiazole

sulfuric acid

N,N-dimethylaniline

→

title compound

[4-(Dimethylamino)phenylazo]benzothiazole

Solvants

water

water

Conditions de réaction

Traitement

1. 1
   workup.ADDITIONDuring addition
2. 2
   Autrewas kept below 5° C
3. 3
   workup.STIRRINGThe mixture was stirred at 0° C. for 15 minutes
4. 4
   workup.STIRRINGstirred for 1 hour
5. 5
   Températureto warm to room temperature
6. 6
   FiltrationThe mixture was filtered
7. 7
   Lavagethe solid was washed with cold water
8. 8
   Autrerecrystallized from methanol
9. 9
   Autrechromatographed (silica gel, 2% methanol in methylene chloride)

Mode opératoire

An ice-cold solution of sodium nitrite (1.65 g, 23.9 mmol) in water (15 mL) was added slowly (via syringe) to a stirring mixture at 0° C. of 2-aminobenzothiazole (3.78 g, 25.2 mmol) in water (50 mL) and concentrated sulfuric acid (7.0 mL, 126.7 mmol). During addition, the temperature was kept below 5° C. The resultant orange mixture was stirred at 0° C. for 15 minutes, then N,N-dimethylaniline was added dropwise causing the mixture to turn dark brown-black. The mixture was stirred at 0° C. for 15 minutes, an aqueous solution of sodium acetate (4.32 g in 20 mL of water) was added dropwise, stirred for 1 hour, basified with 25% sodium hydroxide solution to a pH ~12 and allowed to warm to room temperature. The mixture was filtered, the solid was washed with cold water, recrystallized from methanol, then chromatographed (silica gel, 2% methanol in methylene chloride) to give the title compound as a green solid, mp 243-246° C.

Source