Hydrochloric Acid → 4,5-Dibromo-2-(4-fluorophenyl)pyridazin-3(2H)-one

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Reaction Conditions

Reaction Steps

Mucobromic acid (5.0 g, 19.4 mmol) dissolved in acetic acid (110 mL) was treated with 4-fluorophenyl hydrazine.HCl, and the heterogeneous mixture brought to reflux at a bath temperature of 115° C. for 15 hours. During the course of reaction, the mixture became a homogeneous deep red solution, and upon cooling to 23° C., a crystalline precipitate formed. The solution was poured into ice water (1000 mL) and stirred for 20 minutes. The yellow/brown crystals were filtered off, washed with additional cold water, and dried in vacuo to provide 5.8 g (86%) of product. (J. Het. Chem., 1993, 30, 1501; Heterocycles 1985, 23, 2603) 1H NMR (300 MHz, DMSO-d6) δ 7.31-7.41 (m, 2H), 7.57-7.64 (m, 2H), 8.29 (s, 1H). MS (DCI+) m/z 347 (Br79Br79 M+H)+, m/z 349 (Br79Br81 M+H)+, m/z 364 (Br79Br79 M+NH4)+, and m/z 366 (Br79Br81 M+NH4)+.

Provenance & Evidence