Benzene → 1-Phenyl-3-methyl-4-(p-methylthiophenylcarbamoyl)-2-pyrazolin-5-one

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Reaction Steps

The mixture of 2.6 g of 1-phenyl-3-methyl-2-pyrazolin-5-one, 75 ml of benzene, 1.8 g of triethylamine and 2.5 g of p-methylthiophenylisocyanate is stirred at ambient temperature and allowed to stand overnight. It is evaporated; the residue taken up in methanol, the solution is filtered and combined with the mixture of 10 ml of 5 N hydrochloric acid and 250 ml of water. The precipitate formed is collected, washed with water, dried, triturated with diethyl ether and dissolved in 2 N aqueous sodium hydroxide. The solution is filtered, acidified with 5 N hydrochloric acid, the precipitate washed with water, dried, triturated with methanol and recrystallized from ethyl acetate, to yield the 1-phenyl-3-methyl-4-(p-methylthiophenylcarbamoyl)-2-pyrazolin-5-one melting at 196°-199°.

Provenance & Evidence