2,4-Dichlorophenyl isocyanate → 3-(2,4-Dichlorophenyl)-6-fluoroquinazoline-2,4(1H,3H)-dione

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Reaction Steps

2,4-dichlorophenyl isocyanate (18.8 g, 0.10 mol) is introduced in portions at room temperature into a solution of ethyl 5-fluoroanthranilate (18.3 g, 0.10 mol) in hexane (120 ml). After addition is complete, the mixture is stirred under reflux for 2 hours. 3.60 ml of a 30% strength solution of methanolic sodium methoxide (0.020 mol) are metered in and the mixture is stirred under reflux for a further 2 hours, ethanol and methanol being distilled off. After cooling, the product is filtered off with suction and washed with 3×15 ml of hexane. The hexane-moist precipitate is treated with dilute hydrochloric acid and the residual hexane is removed by azeotropic distillation. The product is then filtered off with suction, washed with water and dried. 31.2 g of 3-(2,4-dichlorophenyl)-6-fluoro-2,4(1H,3H) -quinazolinedione (yield: 96.0% of theory) of melting point 312° to 314° C. are obtained.

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