Benzimidazolone-dioxazines

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... 

Preparation of the benzimidazolone-dioxazine pigments usually involves a multi-step synthesis followed by finishing. A typical reaction scheme depicting the synthesis of the unsubstituted derivative, but which can be generalized for all other substituents, is shown in Figure 20-15. 

Figure 20-15 Typical synthesis of benzimidazolone-dioxazine pigments.

The proof of this hypothesis, and particularly of the role of supramolecular conjugation in explaining the relationship between color and constitution of organic molecules, is provided by the absorption spectra of the carbazole-dioxazine pigment and the three benzimidazolone-dioxazine pigments shown in Figure 20-18. 

Figure 20-18 Absorption spectra (DMSO) of benzimidazolone-dioxazine pigment versus carbazole-dioxazine pigments.

Like most high-performance pigments, benzimidazolone-dioxazines are expected to be more highly priced than classical pigments. However, their outstanding tinctorial strength should reflect their overall value within reasonable limits, in line with the following ... 

After two years of Florida exposure in acrylic melamine formaldehyde (A/MF) lacquers, the parent, unsubstituted benzimidazolone-dioxazine shows at least similar durability to Pigment Violet 23. 

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. 

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. 

Benzimidazolone-dioxazine pigments are expected to become available in all typical color delivery forms of organic pigments. 

There are no standard specifications yet for benzimidazolone-dioxazine pigments. Benzimidazolone-dioxazine pigments are proprietary pigments from Clariant. 

The combination of benzimidazolone moieties with the triphenedioxazine chro-mophore leads to imidazolone-annellated triphenedioxazine pigments, also called benzimidazolone-dioxazine pigments (4). In these pigments, the carbazole fragments of P.V. 23 are replaced by benzimidazolone moieties (Figure 20.6). 

R. Born Mixed crystals of benzimidazolone dioxazine compounds , EP 1201718 (2002). 

M.U. Schmidt, P. Kempter, R. Born Process for preparing new crystal polymorphs of a methyl-substituted benzimidazolone-dioxazine pigment , EP 1199309 (2002). 

To obtain the necessary fastness properties, high-quality pigments are generally used for security printing. The range of suitable products covers disazo, disazo condensation, benzimidazolone, naphthol AS, isoindolin, perinone, anthanthrone, dioxazine and quinacridone pigments. 

---