Dioxazine chemistry

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. 

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-... 

Substituents of dioxazines, oxathiazines or dithiazines are generally close to, or attached to, a heteroatom. Consequently the reactivity of any substituents is influenced by the adjacent heteroatoms. For example, halogens bonded to a carbon a to a heteroatom are readily displaced. The substituent reactivity is usually predictable on the basis of the chemistry of the functional groups of which they are comprised. 

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