Pigments color compounding

The red pigment isolated in crystalline form from the reaction products of 1-methyl-3,4-benzoquinone and 4-hydroxyproline ethyl ester was identified as 4-(4 -hydroxy-2 -carbethoxy-l -pyrrolidyl)-5-methyl-l,2-benzoquinone (115).283 This highly colored compound should probably be formulated as a zwitterion (116). Similar pigments can be obtained by the interaction of o-benzoquinone with proline, hydroxyproline, pyrrolidine, and glycine. Suzuki has shown... 

The heterocycle of anthocyanidins is a pyrilium kation. Anthocyanidins are typically not found as free aglycones, with the excepton of the following widely distributed, colored compounds Pelargonidin (orange-red 1.45), cyanidin (red 1.46), peonidin (rose-red 1.47), delphinidin (blue-violet 1.48), petunidin (blue-purple 1.49), and malvidin (purple 1.50). A convenient mnemonic is PCP-DPM. The most common anthocyanidin is cyanidin. These compounds are present in the vacuoles of colored plant tissues such as leaves or flower petals. The color of the pigment depends on... 

Transition metal family elements often form colored compounds. Many of these colored compounds are used as pigments in paints. Chromium oxide is a green pigment. Lead chromate is a yellow pigment. 

Carry fat-soluble vitamins and natural color compounds, for example, yellow pigments to improve the color of egg yolks red and orange colors for feeding salmon. 

In the United States two classes of color additives are recognized colorants exempt from certification and colorants subject to certification. The former are obtained from vegetable, animal, or mineral sources or are synthetic forms of naturally occurring compounds. The latter group of synthetic dyes and pigments is covered by the Color Additives Amendment of the U.S. Food, Drug and Cosmetic Act. In the United States these color compounds are not known by their common names but as FD C colors (Food, Drug and Cosmetic colors) with a color and a number (Noonan 1968). As an example,... 

An all aqueous printing compound that provides a lustrous metallic print in a neutral off-white color. With pigment colors being added, unique metallic appearing prints can be achieved to give novelty prints with excellent durability. A variety of tints can be achieved by adding small amounts of concentrated colors. 

Oxidation has an important effect on the color of fats and oils. Although oxidation bleaches the carotenoid pigments, it tends to develop the color of other types of coloring material and, in certain cases, even develops colored compounds of qui-noid nature from the fatty acids or acylglycerols of the oils. Cottonseed and, in certain cases, soybean oil are subject to marked darkening upon oxidation. The effect of oxidation or aeration on the color stability of oils is shown in Figure 7 (7). 

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