Pyridine → 1,3-Dimethyl-5-[4-chloro-2-(2,6-dichlorophenoxy)phenylcarbamoyl]-2-thiobarbituric acid

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Reaction Conditions

Reaction Steps

15.5 g (0.09 mol) of 1,3-dimethyl-2-thiobarbituric acid, 8.8 g (1.1 mol) of pyridine and 0.9 g of 4-dimethylaminopyridine are dissolved in 65 ml of dichloromethane and the solution is cooled to 0° C. Then 10.2 g (0.094 mol) of ethyl chloroformate are added dropwise over 1 hours. The mixture is stirred for 12 hours at 0° C. and then for 7 hours at room temperature. The bulk of the solvent is evaporated off, a solution of 26.1 g (0.09 mol) of 4-chloro-2-(2,6-dichlorophenoxy)aniline in 360 ml of ethanol and 30 ml of dimethylformamide is added and the mixture is boiled under reflux with stirring for 6 hours. The reaction mixture is then cooled and the resultant crystalline precipitate is isolated by filtration and, if necessary, is recrystallised from dioxane/ethanol. Melting point 254°-257° C.

Provenance & Evidence