Dioxazine violet pigments

The general class of compounds known as dioxazines, or more systematically as triphenodioxazines, exhibit colors ranging from yellow to violet, in the soUd state, as a manifestation of their respective chemical and crystallographic structures [1]. 

The class is characterized by the parent of the series 1, a condensed pentacyclic structure in which two oxazine rings with opposite orientation are sandwiched between three aromatic carbocycles of which the central one is quininoid  

The symmetrical planar and conjugated quininoid structure is a very efficient chromophore, thus imparting intense coloration to those compounds of which it is a structural component. 

The sulfonated derivatives of the parent structure, discovered in 1928 (Kranzlein et al, Farbewerke Hoechst), afford colorants which can be used as direct dyes on cotton, but the parent triphenodioxazine, an orange solid, has no technical importance as a colorant. It was not until 1952, however, that a tinctorially strong violet pigment derived from a 9,10-dichlorotriphenodioxazine was patented [2] and ultimately designated as Pigment Violet 23. 

High Performance Pigments. Edited by Edwin B. Faulkner and Russell J. Schwartz Copyright 2009 WILEY-VGH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-31405-8 

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Hayashi, Y. and Sakaguchi, I. (1982). Stable dioxazine violet pigment production from metastable form—by heating aqueous suspension with aliphatic or alicyclic ketone or acetate. Sunmitomo Chem. Co. Ltd Patent DE 3 211 607 AL [260t]... 

Benzil, 3 594 14 594 Benzilonium bromide, 4 359t Benzimidazoles, microwave-assisted synthesis of, 16 574-575 Benzimidazolethiols, 25 197 Benzimidazolone dioxazine, 19 446 Benzimidazolone pigments, 19 432 433 Benzimidazolone Violet, pigment for plastics, 7 367t Benzine, 3 597... 

The dioxazine ring system is the source of some valuable violet pigments, such as Cl Pigment Violet 23 (6.211). This colorant is obtained by condensing 3-amino-9 ethylcarbazole with chloranil. Sulphonation of the pigment gives the dye Cl Direct Blue 108. Triphenodioxazines have recently been the source of some blue reactive dyes [241-Examples are known of symmetrical bifunctional structures (6.212 NHRNH = alkylenediamine, Z = haloheterocyclic system) and unsymmetrical monofunctional types such as 6.213 [37]. 

At present, dioxazines no longer enjoy commercial significance as dyes. The pigments industry shows little interest in substituted derivatives of the described parent structure other than this violet pigment. 

Dioxazine. Carbazole Violet (Pigment Violet 23) is a bluish violet pigment that is uncommonly strong, resistant to solvents, and shows fair weatherfastness. It is used primarily as a shading pigment with copper phthalocyanines and for toning whites in a variety of systems. 

Alizarine Maroons. This pigment is an extremely blue-shade red, virtually putting it in violet color space. In fact, many old-time colorists call alizarine maroon the poor man s carbazole dioxazine violet. Moderate heat stability coupled with bleed resistance has supported this pigment for years in modest demand applications. 

PCBs and PCDDs. In Diarylide Yellow manufacture, the use of formate buffer to enhance pigment transparency for offset ink was discontinued in the nineteen seventies, when it was realized that polychlorinated biphenyls were being produced as an undesirable by-product of the coupling reaction. In Phthalocyanine Blue crude synthesis, the commonly used solvent, trichlorobenzene, was also discontinued in the US, as a potential source of poly-chlorinated biphenyls. More recently, use of chloranil, manufactured from chlorinated phenols, has been discontinued in the synthesis of dioxazine violet crude and sulfonated dioxazine acid dyes, so as to minimize by-product formation of polychlorinated dibenzodioxins and dibenzofurans (PCDDs/PCDFs). A new grade ofhigh purity chloranil is now produced from hydroquinone for dye and pigment manufacture. 

Dioxazine violet B. See Pigment violet 37 Dioxazine violet RL. See Pigment violet 23 1,1 -Dioxide-1,2-benzisothiazol-3(2H)-one sodium salt. See Saccharin sodium anhydrous 1,1-Dioxide tetrahydrothiofuran 1,1-Dioxidetetrahydrothiophene. See Sulfolane Dioxime-p-benzoquinone Dioxime-1,4-cyclohexadienedione Dioxime-2,5-cyclohexadiene-1,4-dione. See p-Quinone dioxime... 

Carbazole Dioxazine Violet, B.L. Kaul and L. Wihan, Pigment Handbook, 609, Vol. 1, Ed. Peter A. Lewis, John Wiley N.Y. (1988). 

Imidazolone-annellated triphenedioxazine pigments, also called benzimidazo-lone-dioxazine pigments, are a relatively new class of violet pigments with very good fastness properties and extremely high color strengths. The stractural formula is shown in Figure 20.1. 

Violet pigments cobalt violet, dioxazine violet, quinacridone violet... 

Carbazole dioxazine violets are semitransparent masstone pigments having high tint... 

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