Meclofenamic acid → 2-[(2,6-Dichloro-3-methylphenyl) amino]-benzoic acid, 2-(aminothioxomethyl)hydrazide

Participants

Reaction Conditions

Reaction Steps

Oxalyl chloride (2.85 g, 22.5 mmol) in 10 ml of methylene chloride is added dropwise to a 0° C. suspension of 2-[(2,6-dichloro-3-methylphenyl)amino]-benzoic acid (3.17 g, 10.6 mmol) and dimethylformamide (830 μl, 10.6 mmol) in 50 ml of methylene chloride. The clear yellow solution is stirred at 0° C. for 15 minutes and then at room temperature for 30 minutes. The solution is then concentrated in vacuo to give a yellow solid. This solid is added in portions to a suspension of thiosemicarbazide (1.95 g, 21.4 mmol) in 20 ml of pyridine. The suspension is stirred at 0° C for 30 minutes then at room temperature overnight. The reaction mixture is concentrated in vacuo and the residue is partitioned between ethyl acetate and water. The organic layer is concentrated, then slurried with equal volumes of ethyl acetate and hexane. The off-white solid is collected by filtration providing 1.66 g (42%) of 2-[(2,6-dichloro-3-methylphenyl)amino]-benzoic acid, 2-(aminothioxomethyl) hydrazide, mp is undefined.

Provenance & Evidence