Formic Acid → 3-Propyl-1H-quinazoline-2,4-dione

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Reaction Conditions

Reaction Steps

A solution of propyl isocyanate (34.0 g, 0.40 mol) in xylene (100 ml) is metered, at room temperature, into a solution of ethyl anthranilate (66.1 g, 0.40 mol) in xylene (200 ml). After the addition has ended, the batch is stirred at 110° C. for 2 hours. 7.20 ml of a 30% solution of methanolic sodium methylate (0.040 ml) are metered in and the mixture is stirred at 90° C. for a further 2 hours, during which process methanol and ethanol are distilled off. 3.6 ml of 85% formic acid (0.080 mol) are subsequently added and the mixture is stirred at 90° C. for a further hour. After cooling, the product is filtered off with suction, washed with 3×25 ml of xylene, 3×25 ml of ethanol and 3×25 ml of water, and dried. 67.3 g of 3-(propyl)-2,4(1H,3H)-quinazolinedione (yield: 82.4% of theory) of melting point 190° to 191° C. (lit. 187° to 188° C.) are obtained.

Provenance & Evidence