Dioxazine applications

The chemistry of the three most important chemical classes of organic colorants, the azo, carbonyl and phthalocyanine classes, has been dealt with individually in Chapters 3-5 respectively. In this chapter, the chemistry of a further five chemical classes which are of some importance for specific applications is discussed. These classes are the polymethines, arylcarbonium ion colorants, dioxazines, sulfur dyes and nitro dyes. A section of this chapter is devoted to each of these, each individual section contains a description of the principal structural features which characterise the particular colorant type, together with an outline of the chemistry of the main synthetic routes. There are many other chemical types of dyes and pigments that do not fall into the categories previously mentioned, but which are neglected in this text either because they are commercially of little importance or because they have been less extensively investigated. 

P.V.50, produced in Japan, is only of limited regional importance, since it fails to satisfy the increasingly stringent application requirements for organic pigments. Its fastness to light, for instance, is particularly poor 1/3 SD and 1/1 SD letterpress proof prints equal only step 2 on the Blue Scale. Compared to P.V.23, Dioxazine... 

Commercially Available Dioxazine Pigments and Their Application 533... 

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. 

Acylnitroso compounds are best recognized for their ability to participate as dependable 2ir components of Diels-Alder reactions with dienes, and these observations have found substantial application in the total synthesis of natural products (Chapter 3).81 However, Mackay and coworkers have detailed the isolation of 5,6-dihydro-1,4,2-dioxazine 9a (10%) from the reaction of acylnitroso 7a with cyclopentadiene [Eq. (39)]. ... 

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. 

Test results conducted thus far suggest that benzimidazolone-dioxazine pigments should be suitable for almost all applications for the highest performance requirements expected of a high-performance organic pigment. 

Flexible PVC, calendered, extruded or injection moulded Heat stability up to 200°C Non migratory, non chalking light stability depending on application Cadmium pigments, red and yellow toners Azo-condensation Polycyclics Lead pigments Phthalocyanines Bis-arylamides Isoindolinones Iron oxide Dioxazin Special monoazos... 

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