Pigments synthetic organic colors

Pigment. Synthetic organic pigments are inert, stable, coloured substances insoluble in water and organic solvents, such as the oils commonly used as vehicles in paint manufacture. They are used also in the mass coloration of plastics. Physical form is of paramount importance in ensuring maximum colouring power and reflectance. 

The first synthetic organic pigments were used to shade or tone the weaker colorants and became known as toners. Metal toners usually contain one sulfonic acid group and often a carboxyUc acid group. The pigment is rendered iasoluble, ie, laked Ai a heavy metal cation. An example of a calcium salt is Lithol Rubine BK [5858-81-1] Vhl) (Cl Pigment Red 57 Cl 15850). 

Color Additives. The FDA has created a unique classification and strict limitations on color additives (see also CoLORANTS FOR FOOD, DRUGS, COSMETICS, AND MEDICAL DEVICES). Certified color additives are synthetic organic dyes that ate described in an approved color additive petition. Each manufactured lot of a certified dye must be analyzed and certified by the EDA prior to usage. Color lakes are pigments (qv) that consist of an insoluble metallic salt of a certified color additive deposited on an inert substrate. Lakes are subject to the color additive regulations of the EDA and must be certified by EDA prior to use. Noncertifted color additives requite an approved color additive petition, but individual batches need not be EDA certified prior to use. 

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. 

Of all synthetic organic pigments, the azo compounds are by far the most important, making up 48% of the total. Some 66 million lb are made each year in the U.S. Second in importance are the phthalocyanines, produced at the 33 million lb level. By color, red, blue, and yellow pigments are all equally important. 

Juices extracts (liquorize), spirits (orange, lemon), syrups (black currant), tinctures (ginger), and aromatic waters Mineral pigments (iron oxides), natural colorants, anthocyanins, carotenoids, chlorophylls riboflavine, red beetroot extract, and caramel synthetic organic dyes azo compounds... 

The synthetic color industry dates back to the accidental discovery of the first synthetic organic dye (mauve) in 1856. Sir William Henry Perkin, in an unsuccessful attempt to synthesize quinine, succeeded in obtaining a violet dye by the oxidation of aniline. This led other scientists to experiment and discover many new colors with superior properties to the natural pigments and extracts. The use of these new and different colors in foods, drugs, and cosmetics began almost immediately because of their tinctorial value, stability, and the many shades in which they were available. 

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