Carbazole dioxazine violets

Derived from tribenzodioxazine (79), coloured compounds of this type have been known since 1928 and have been used as reddish-blue direct dyes for cotton. An important violet, Carbazole Dioxazine Violet (80), was prepared by condensation of 3-amino-A-ethylcar-bazole with chloranil followed by cyclization of the intermediate diimine and pigmentary conditioning (56GEP946560). A second useful synthesis involves condensation of an o-alkoxyarylamine with chloranil followed by cyclization (65C242). 

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. 

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

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

CAS 6358-30-1 EINECS/ELINCS 228-767-9 Synonyms Carbazole violet Cl 51319 8,18-Dichloro-5,15-diethyl-5,15-dihydrodiindolo [3,2-b 3, 2 -m] triphenodioxazine Dioxazine violet RL Classificatbn Oxazine color Empirical Cs4H22Cl2N402 Properties M.w. 589.49 Toxicology TSCA listed... 

As part of a general program to improve performance characteristics of the traditional carbazole dioxazine pigment in such areas as bleed resistance, solvent fastness and heat stability, and at the same time to extend the range of shades beyond violet, a new class of dioxazine pigment bearing quinoxalinedione and benzimidazo-lone moieties in place of carbazole residue has been developed at Clariant (Figure 20-14). By simple manipulation of the substituents on the heterocyclic... 

Benzimidazolone-dioxazine pigments identified for commercialization thus far are red-violet to reddish-blue in shade. They are characterized by an exceptionally high tinting strength, and their heat stability and resistance to aggressive solvents and plasticizers is much superior to that of carbazole dioxazine pigments. 

Other chemical types of high-performance organic pigments are exemplified by the tetrachloroisoindolinone 222 (C. I. Pigment Yellow 110) and the dioxazine 223 (Carbazole Violet, C. I. Pigment Violet 23). Considerable research has been carried out in an attempt to exploit the potential of metal complex chemistry to provide high-performance pig-... 

Most pigments derived from vat dyes are structurally based on anthraquinone derivatives such as indanthrone, flavanthrone, pyranthrone, or dibromoan-thanthrone. There are other polycyclic pigments which may be used directly in the form in which they are manufactured. This includes derivatives of naphthalene and perylene tetracarboxylic acid, dioxazine (Carbazole Violet), and tetrachloro-thioindigo. Quinacridone pigments, which were first introduced in 1958, and recently DPP pigments have been added to the series. 

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. 

The universally applicable dioxazine pigment, especially Pigment Violet 23, which is distinguished by good color strength, is commercially important. It is produced by the reaction of 3-amino-N-ethylcarbazole and chloranil in o-dichloro-benzene at temperatures between 130 and 150 °C followed by oxidative ring closure to the dioxazine in the presence of benzenesulfonyl chloride. The 3-amino-N-ethylcarbazole required for the synthesis is produced from carbazole by N-alkyla-tion, e.g. with diethyl sulfate or ethyl chloride, and nitration followed by the reduction to the amine. 

---