PRODUCTION OF DIOXAZINE COMPOUND

PURPOSE:To obtain the titled compound useful as dyes, pigments, etc. by using a small amount of a reaction promoter at a low cost, by subjecting a specific benzoquinone derivative to cyclization reaction while heating in an inert organic solvent in the presence of an inorganic acid, etc. CONSTITUTION:A compound expressed by formula I (R represents 1-4C alkyl) [example; 2,5-dichloro-3,6-bis(9-ethyl-3-carbazolylamino)-1,4-benzoqu-inone, etc.] is cyclized in an inert organic solvent (preferably chlorobenzene, dichlorobenzene, trichlorobenzene or nitrobenzene, or alkylbenzene with >=110 deg.C boiling point) in the presence of an inorganic acid (preferably hydrochloric acid or sulfuric acid) or both the inorganic acid and an oxidizing agent (preferably p- benzoquinone, etc.) while heating preferably at 110-200 deg.C to obtain the aimed compound expressed by formula II (X, and X2 represent H or Cl).