Benzimidazolone azo pigments

Figure 9.3 Intermolecular association in the crystal structure of a benzimidazolone azo pigment...

Although, strictly speaking, it would be more precise to refer to such compounds as benzimidazolone azo pigments, the convention of listing them as benzimidazolone pigments will be followed. 

In the red pigment, these bands consist of a sequence of individual molecules which are interlocked with each other (30). In terms of molecular structure, benzimidazolone pigments thus represent an entirely new type of azo pigment. 

Recently, combinations of DPP Pigments with yet other pigments like thiazine indigo, benzimidazolone triphenodioxazine, anthraquinones, azo pigments, benzi-midazolones, isoindolinones " have appeared in the literature. The value of these new combinations has yet to be established. 

Because of their physicochemical properties benzimidazolone pigments represent an extremely low toxicological and environmental risk. like other azo pigments, the benzimidazolone pigments have very high oral LD o values. Exposure to fine dust should however be avoided in the workplace, and normal industrial hygiene procedures for handling chemicals should be practiced. 

Table 23 lists commercially available benzimidazolone pigments. It should be noted that pigments in the red range are often derived from a diazonium component carrying a methoxy group in ortho position to the azo group. 

Benzimidazolone pigments are actnally monoazo pigments but the convention within the indnstry is to not use the azo descriptor they are classified as high-performance pigments. All the pigments in this class are derived from coupling... 

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... 

Benzimidazolone pigments are azo colorants that derive their name from the benzimidazolone group which is introduced as part of the coupling component. Apart from one exception ) there are two coupling components of commercial importance 5-acetoacetylaminobenzimidazolone (1) and 5-(2 -hydroxy-3 -naphthoylamino)-benz-imidazolone [Naphtolon ] (2) (see Figure 10-1). 

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