Other Imidazolone-Annellated Triphenedioxazine Pigments

The p-phase is formed with CFjCOOH and subsequent dilutioif (deprotonation) with glacial acetic acid. The s-phase is formed by protonation with CF3COOH and subsequent slow evaporation. Analoguously the C-phase precipitates from a mixture of CF3COOH and o-dichlorobenzene by evaporation. The thermodynamically most stable phases are the a and q polymorphs. 

Other imidazolone-anneUated triphenedioxazines show various shades ranging from reddish violet to reddish blue. This holds for the chlorinated compounds as well as for the chlorine-free compounds (1, X = H). The pigments of both classes generally exhibit very high color strength and excellent fastness properties. The nonchlorinated compounds (1, X = H) shows a high potential as chlorine-free alternative to P.V. 23. 

Most compounds are polymorphic e.g., the chlorine-free compound with R = R = Ph exists in four polymorphs, with different shades of violet. 

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Pigment Blue 80 and other imidazolone-annellated triphenedioxazine pigments are synthesized in an analogous manner as P.V. 23 and its linear isomer. 

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