Chlorosulfonic acid → 3-chloro-1-ethyl-1H-pyrazole-4-sulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

3-Chloro-1-ethyl-1H-pyrazole (0.42 g, 3.2 mmol, the product of Step B) was added to chlorosulfonic acid (2.0 mL, 30 mmol) at room temperature and the mixture was slowly warmed to 100° C., and then heated at 100-110° C. for 2 hours. The reaction mixture was cooled, poured with stirring onto 150 mL of crushed ice, and extracted into diethyl ether (2×100 mL). The ether extracts were combined, washed with water (100 mL), dried over magnesium sulfate and concentrated under reduced pressure to obtain 0.5 g of the title compound as an oil. 1H NMR (CDCl3) δ 8.00 (s, 1H), 4.20 (q, 2H), 1.56 (t, 3H).

Provenance & Evidence