Reaction #2028890

Reaction equation

4-[5-(4-chlorophenyl)-3-trifluoromethyl-1H-pyrazol-1-yl]benzenesulfonamide

acetic acid

chlorine

→

4-[5-(4-chlorophenyl)-4-chloro-3-trifluoromethyl-1H-pyrazol-1-yl]benzenesulfonamide

Yield 75.0%

Solvents

water

Conditions

Workup

1. 1
   OtherA 100 mL three-necked round-bottomed flask equipped
2. 2
   Temperaturewith reflux condenser, gas dispersion tube
3. 3
   workup.STIRRINGThe solution was stirred at room temperature
4. 4
   workup.STIRRINGThe solution was then stirred at room temperature for 1.25 hours
5. 5
   ExtractionThe solution was then extracted three times with ether
6. 6
   Washthe combined ethereal phase washed with brine
7. 7
   Dryingdried over MgSO4
8. 8
   Filtrationfiltered
9. 9
   Concentrationconcentrated in vacuo
10. 10
    Otherto give a white solid
11. 11
    Otherthat was recrystallized from ether/petroleum ether

Procedure

A 100 mL three-necked round-bottomed flask equipped with reflux condenser, gas dispersion tube and provisions for magnetic stirring was charged with 4-[5-(4-chlorophenyl)-3-trifluoromethyl-1H-pyrazol-1-yl]benzenesulfonamide (Example 1) (500 mg, 1.2 mmol) and 50 mL of glacial acetic acid. The solution was stirred at room temperature and treated with a stream of chlorine gas for a period of 15 minutes. The solution was then stirred at room temperature for 1.25 hours and then diluted with 100 mL of water. The solution was then extracted three times with ether and the combined ethereal phase washed with brine, dried over MgSO4, filtered, and concentrated in vacuo to give a white solid that was recrystallized from ether/petroleum ether to provide 390 mg (75%) of 4-[5-(4-chlorophenyl)-4-chloro-3-trifluoromethyl-1H-pyrazol-1-yl]benzenesulfonamide: mp 180°-182° C.; 1H NMR (CDCl3/300 MHz) 7.97 (d, J=6.6Hz, 2H, 7.49 (d, 2H), 7.45 (d, J=6.3Hz, 2H), 7.25 (d, J=6.6Hz, 2H), 5.78 (brs, 2H).

Source