2,3-Dibromo-N-(phenylcarbamoyl)propanamide → 5-Methylidene-1-phenylimidazolidine-2,4-dione

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Reaction Steps

20.0 g of the N-phenyl-N'-(2,3-dibromopropionyl)-urea prepared in accordance with Example 1(b) are suspended in 200 ml of tert.-butanol, 23 g of potassium tert.-butylate (90%) are introduced into the resulting suspension and the mixture is heated under reflux for 1 hour. The solvent is then distilled off under normal pressure and the residue is heated in vacuo for 20 minutes to 120° C. The white crystalline powder obtained is dissolved in 400 ml of water at 60° C. and the solution is filtered and adjusted to pH 1 with dilute hydrochloric acid. The precipitated imidazolidine derivative is filtered off, washed and dried. Yield: 9.0g m.p: 168° - 170° C. (from methanol)

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