What is an azo pigment?
Organic pigments include azo pigments, which contain a nitrogen group; they account for most of the organic red, orange, and yellow pigments. Copper phthalocyanines provide brilliant, strong blues and greens that are unusually colourfast for organic colours.
What is an azo linkage?
Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl. They are a commercially important family of azo compounds, i.e. compounds containing the linkage C-N=N-C. Azo dyes are widely used to treat textiles, leather articles, and some foods.
Why azo dyes are toxic?
Azo dyes that are toxic only after reduction and cleavage of the azo linkage to give aromatic amines, mostly via intestinal anaerobic bacteria. The aromatic amines are met‐abolically oxidized to reactive electrophilic species that covalently bind DNA.
Are azo dyes banned in the US?
Are azo dyes banned in the United States? In the United States, there are no specific regulations that explicitly restrict “azo dyes”. Instead, various aromatic amines that cleaved from azo dyes are restricted or banned.
Which of the following is not an azo dye?
Malachite green has intense green colour prepared by the condensation of dimethylaniline and benzaldehyde. It is chosen as model dye for azo. So, it is not an azo dye.
Are azo compounds stable?
Aryl azo compounds are usually stable, crystalline species. Since diazonium salts are often unstable near room temperature, the azo coupling reactions are typically conducted near 0 °C. The oxidation of hydrazines (R−NH−NH−R′) also gives azo compounds.
What is azo structure?
azo compound, any organic chemical compound in which the azo group (―N=N―) is part of the molecular structure. Most aromatic azo compounds are prepared by the reaction of a diazonium salt with an organic substance that contains easily replaced hydrogen atoms.
Is azo cancerous?
According to current EU regulations, azo dyes based on benzidine, 3,3′-dimethoxybenzidine and 3,3′-dimethylbenzidine have been classified as carcinogens of category 2 as “substances which should be regarded as if they are carcinogenic to man”.