Reactive Dioxazine Dyes

Dioxazine Dyes. The synthetic routes (see below) to almost all dioxazines yield products with a symmetrical structure, resulting in at least two reactive anchors. The highly reactive double-anchor dyes are suitable for both the exhaust and the padding processes. Ecological limits for wastewater are satisfied as a result of a high degree of fixation and low salt requirements in the exhaust process, whereby the latter also has a positive influence on leveling. 

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]. 

The triphenodioxazine chromophore was tested in almost every class of dyes, but only recently has it been introduced into reactive dyes. Dioxazines were investigated in some of the earliest work on reactive dyes in the late 1950s, and they are included in some of the first patents covering reactive anchors and reactive dyes [42], In particular, compound 21 was invoked as a chromophore, with reactive anchors attached to the free amino groups of the molecule. 

The launching of these new products initiated research by other dye manufacturers. This led to numerous new dioxazine reactive dyes (Examples see Table 2.3). 

The triphenodioxazine chromophore can be converted to a reactive dye by incorporating anchors that are attached to the dioxazine core either directly or via bridging groups. The first patents, like the first commercial products, were based almost exclusively on the use of bridging groups. The usual starting material is 2-chloro-5-nitrobenzenesulfonic acid (27), which is treated with a diamine (28). 

Reactive dyes are colored compounds that contain groups capable of forming covalent bonds between dye and substrate. Approximately 80-90% of reactive dyes are azo dyes. The other chromogenic classes are anthraquinones, dioxazines, phthalocyanines, and some 1 1 copper azo complexes. Reactive 1 2 complex leather dyes were also commercially manufactured for a short time. Constitution and producer have not been disclosed. 

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