Thionyl Chloride → 3-Chloroisatoic anhydride

Participants

Reaction Steps

468 gm of N-ethoxycarbonyl-3-chloro-anthranilic acid (m.p. 111°-114° C) were refluxed in 1500 ml of dioxane with 420 ml of thionyl chloride for 3 hours while stirring. Thereafter, the reaction solution was evaporated in vacuo until crystallization started, and then cooled. The precipitate was collected by suction filtration and washed with ether. 8-Chloro-2H-3,1-benzoxazine-2,4(1H)-dione, m.p. 225°-230° C, was obtained.

Provenance & Evidence