反应详情

Heated was a mixture of N,N′-dibenzylurea 12.02 g (50.0 mmol) and malonic acid 5.20 g (50.0 mmol) in acetic anhydride 50.0 mL (530 mmol, 10.6 equivalents) at 70° C.-75° C. for 14 hours under a nitrogen atmosphere. Then, removed were the volatile materials under the reduced pressure and distributed the residue between layers of 2 M sodium hydroxide 250 mL and ether 200 mL. Separated was the alkaline aqueous layer and after washing with ether, neutralized with concentrated hydrochloric acid under cooling in ice-water bath (pH 2-3). Extracted was the neutrallized aqueous solution with chloroform, washed with water, and dried over sodium sulfate. Removal of the solvent under reduced pressure gave 1,3-dibenzylbarbituric acid 14.7 g as pale yellow crystalline powder (95.6% yield).

1. temperatureHeated
2. customThen, removed
3. customSeparated
4. washafter washing with ether, neutralized with concentrated hydrochloric acid
5. temperatureunder cooling in ice-water bath (pH 2-3)
6. extractionExtracted
7. washwashed with water
8. dry with materialdried over sodium sulfate
9. customRemoval of the solvent under reduced pressure