Sulfuric Acid → 1,4-Benzoxazine-2,3-dione

Participants

Reaction Steps

103 parts of isatin are introduced slowly into a solution of 190 parts of potassium peroxydisulfate in 1,300 parts of 90% strength sulfuric acid at from 0° C. to 10° C. The mixture is then stirred for 10-20 minutes, after which it is poured onto ice. The product is filtered off and dried, giving 110 parts of 2,3-dioxo-1,4-benzoxazine, of melting point 285° C. (with decomposition).

Provenance & Evidence