反应详情

温度

65 °C

In a four-necked flask equipped with stirrer, reflux cooler, thermometer and dropping funnel, 31 g of 5-fluoroanthranilic acid were dissolved in 280 ml of ethyl acetate at 50° C. To this were added dropwise in the course of 20 minutes 37.6 g of molten 2,4-dichlorophenyl isocyanate from a heatable dropping funnel. The internal temperature increased to 65° C., at which the reaction mixture thickened, but still remained stirrable. It was further stirred for 2 hours under reflux, then cooled to 70° C. and 39.5 g of concentrated sulphuric acid were added dropwise in the course of 10 minutes. The internal temperature again increased to reflux temperature. At this temperature the mixture was further stirred for 4.5 hours, a readily stirrable suspension resulting. The mixture was then cooled to room temperature, the product filtered off by suction and washed twice on the filter each time using 75 ml of ethyl acetate. After drying, 59 g of 3-(2,4-dichlorophenyl)-6-fluoroquinazoline-2,4-dione were obtained having a melting point above 250° C., in a purity of 99% and in a yield of 89.8% of theory.

1. customIn a four-necked flask equipped with stirrer
2. temperaturereflux cooler
3. temperatureunder reflux
4. temperaturecooled to 70° C.
5. temperatureThe internal temperature again increased
6. temperatureto reflux temperature
7. stirringAt this temperature the mixture was further stirred for 4.5 hours
8. customa readily stirrable suspension resulting
9. temperatureThe mixture was then cooled to room temperature
10. filtrationthe product filtered off by suction
11. washwashed twice on the
12. filtrationfilter each time
13. customAfter drying