Hydrochloric Acid → 6,7-Dichloroquinazoline-2,4(1H,3H)-dione

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Reaction Conditions

Reaction Steps

2-Amino-4,5-dichlorobenzoic acid (920 mg) and urea (2.75 g) were stirred at 160° C. After 6 hours the mixture was cooled to 100° C. and an equivalent volume of water was added while stirring was continued for 5 minutes. The formed precipitate was filtered off and washed with water to yield a solid cake that was suspended in a solution of 0.5 N NaOH in water. The suspension was heated to boil for 5 minutes and then cooled to r.t. The pH was adjusted to about 2 with HCl and the quinazoline-dione was filtered off. After washing with a mixture of water and methanol the product was dried in vacuo to yield 994 mg (94%) of a solid. 1H-NMR (DMSO-δ6) δ (ppm) 7.89 (s, 1H), 7.33 (s, 1H).

Provenance & Evidence