Water → 4-(4-chloro-benzylsulfanyl)-3,5-dimethyl-1H-pyrazole

Participants

Reaction Steps

To a solution of crude 3-(4-chloro-benzylsulfanyl)-pentane-2,4-dione [prepared as described above from 3-chloro-pentan-2,3-dione (1.03 g, 7.63 mmol) and 4-chlorobenzyl mercaptan (1.21 g, 7.63 mmol)] in ethanol (60 mL) was added hydrazine hydrate (0.713 mL, 22.9 mmol) and p-toluenesulfonic acid monohydrate (ca. 25 mg). The solution was heated to reflux and stirred for 15 hours. The reaction mixture was allowed to cool to room temperature, and water (300 mL) was added. The precipitate that formed was removed by filtration, washed with water, and dried to provide 1.38 g (72%) of the product as a white solid: 1H NMR (CDCl3) δ 7.17 (d, J=8.4 Hz, 2H), 6.92 (d, J=8.4 Hz, 2H), 3.57 (s, 2H), and 2.02 (s, 6H) ppm. 13C NMR (CDCl3) δ 137.2, 132.7, 130.3, 128.3, 105.2, 39.9, 10.7 ppm.

Provenance & Evidence