Chlorine → 4-[5-(4Chlorophenyl)-4-chloro-1h-pyrazol-1-yl]benzenesulfonamide

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Reaction Steps

4-[5-(4-Chlorophenyl)-1H-pyrazol-1-yl]benzenesulfonamide from Step 2 (3.0 g, 9 mmol) was dissolved in 50 mL of acetic acid, and 9 mL of 1M chlorine in acetic acid was added dropwise. The mixture was stirred for 16 hours when sat. aq. sodium bicarbonate solution was slowly added until the mixture was neutral to pH paper. The mixture was extracted with ethyl acetate (3×50 mL), combined and washed with sat. aq. sodium bicarbonate and with brine, dried over magnesium sulfate, filtered, and concentrated. The resultant product was recrystallized from isopropanol to yield 2.6 g (78%) of a white solid: mp 168-171° C. (dec); 1H NMR (DMSO-D6 /300 MHz) 8.08 (s, 1H), 7.83 (d, J=8.7 Hz, 2H), 7.55 (d, J=8.7 Hz, 2H), 7.46 (brs, 2H), 7.44 (d, J=8.7 Hz, 2H), 7.35 (d, J=8.7 Hz, 2H). Anal. Calc'd for C15H11N3SO2Cl2 : C, 48.93; H, 3.01; N, 11.41. Found: C, 49.01; H, 2.97; N, 11.41.

Provenance & Evidence