Carbonyl colorants pigments

The synthesis of carbonyl colorants uses a wide diversity of chemical methods, in which each individual product essentially has its own characteristic route. This is in complete contrast to the synthesis of azo dyes and pigments (Chapter 3) where a common reaction sequence is universally used. The subject is too vast to attempt to be comprehensive in a text of this type. The following section, therefore, presents an overview of some of the fundamental synthetic strategies which may be used to prepare some of the more important types of carbonyl colorants. 

Commercial anthraquinoid vat dyes are dye preparations that consist of a vat-table colored pigment and a dispersing agent. Such vattablepigments are polycyclic quinoid compounds that contain two or more carbonyl groups in a closed system of conjugated double bonds (Section 3.4). 

In terms of fastness properties, carbonyl dyes and pigments are often superior to their azo counterparts. They are thus commonly the colorants of choice when high technical performance is demanded by a particular... 

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. 

Carbonyl pigments of a variety of types may also be classed as high-performance products. These include some anthraquinones, quinac-ridones, perylenes, perinones, isoindolines and diketopyrrolopyrroles. The chemistry of these groups of colorant is discussed in Chapter 4. Some representative examples of chemical structures of important high-performance carbonyl pigments are illustrated in Figure 9.4. 

Synonyms Benzimidazolone yellow FI4G BenzimidazoloneyellowR151Y Benzoic acid, 2-(1-(2,3-dihydro-2-oxo-1H-benzimidazol-5-yl) amino) carbonyl)-2-oxopropyl) azo) Cl 13980 Cl pigment yellow 151 Classification Monoazo color... 

Quinones constitute a unique class of carbonyl compounds. They are cyclic conjugated diketones. The simplest example is 1,4-benzoquinone (eq. 7.44). All quinones are colored, and many are naturally occurring pigments that are used as dyes. Alizarin is an orange-red quinone that was used to dye the red coats of the British army during the American Revolution. Vitamin K is a quinone that is required for the normal clotting ofblood. 

Zollinger, H., "Ch. 8. Carbonyl Dyes and Pigments," in H. Zollinger, Color Chemistry Synthesis, Properties, and Applications of Organic Dyes and Pigments, 3d ed. Zurich VHCA/Wiley-VCH, 2003. 

For the majority of perylene pigments, both color and stability properties derive from electronic pi-pi interactions. However, for Pigment Violet 29 (6), the unsubstituted diimide, hydrogen bonding between the imide hydrogens and the carbonyl groups is also possible, and is undoubtedly the reason for the added stability of this perylene pigment. 

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