Acetic Acid → 6-Chloro-2-(3-chloropropyl)-2,3-dihydro-3-hydroxy-4H-1,3-benzoxazin-4-one

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Reaction Steps

6-Chloro-2-(3-chloropropyl)-2,3-dihydro-3-hydroxy-4H-1,3-benzoxazin-4-one was prepared by adding 250 ml. of glacial acetic acid saturated with hydrogen chloride gas to 37 g. of 5-chlorosalicylhydroxamic acid. 4-Chlorobutyraldehyde diethyl acetal (34 g.) and 50 ml. of glacial acetic acid saturated with hydrogen chloride gas were then added simultaneously with stirring at a rate to maintain a temperature of 25° to 40° C. The resulting mixture was stirred and heated at 55° to 60° C. for 2 hours and then allowed to stand at room temperature overnight. Mixture was poured into a mixture of ice and water, and when oil solidified it was removed by filtrating, washed with water, and air-dried. The crude product weighed 31.5 g. and melted at 70°-75° C. A sample recrystallized from ligroin at 80°-81° C.

Provenance & Evidence