Heterocyclic anthraquinone pigments

listed under Constitution No. 58000 1, continues to be used only in the USA. The pigment affords brilliant, bluish shades of red. Traces of iron as an impurity adversely affect the full shades and shift the color towards duller and bluer shades. The pigment is not fast to common organic solvents, especially to esters and ketones. It therefore lacks stability to overcoating. Its lightfastness, particularly in tint, is poor. P.R.83 is used in paints for toys, in packaging printing inks, especially for soap and butter, and in artists colors. 

Commercial interest inP.V.5 l, Constitution No. 58055 1,has declined considerably. The pigment continues to be used in industrial paints, especially throughout the USA. Its full shade is a brilliant, deep bluish maroon. In white reductions, the pigment produces clean, reddish violet shades. It lacks tinctorial strength and the coatings are fast to neither acid nor alkali. P.V.5 1 is also not very lightfast, which practically precludes its use in products for exterior application, particularly in reduced shades. 

5 1 is used to a certain extent in PVC. Plasticized PVC systems are fast to bleeding and reasonably lightfast in full shades. Addition of Ti02, however, markedly affects its lightfastness. The pigment is heat stable up to 170°C. 

As a group, these pigments include compounds whose heterocyclic system is formally derived from the anthraquinone nucleus. 

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This chapter classifies polycyclic pigments by chemical constitution. The resulting classes include aminoanthraquinones, hydroxyanthraquinones, heterocyclic and polycarbocyclic anthraquinone pigments. 

The anthrapyrimidine sub-group of the polycyclic pigments are heterocyclic anthraquinones. 1,9-anthrapyrimidme, which is not used commercially, is the parent structure for this group this, and its substituted derivatives, are obtained by condensation of 1-aminoanthraquinone. The principal member is anthrapyrimidine yellow. Cl 68420/Pigment Yellow 108 Colour Index, 1971), a compound mainly used in paints (Herbst and Hunger, 1997). 

Examples of tetrapyrroles include porphyrins and porphyrin derivatives and more specifically, chlorophylls, heme pigments and bilins. Examples of tetra-terpenoids or carotenoids include carotenes and xanthophylls. Examples of quinines include benzo-quinones, anthraquinones and naphthiquinones. Examples of oxygen-containing heterocyclic compounds such as flavonoids include anthocyanins and flavonols. Examples of nitrogen-containing heterocyclic compounds include indigoids and indole derivatives, such as betalaines and eumelanins, and substituted pyrimidines such as pterins and purines. 

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