How do azo dyes work?

Azo dyes are synthetic compounds containing an azo bond –N=N-, obtained mainly from the aromatic amine substrate, nitro and nitroso. The synthesis processes rely on the use of an appropriate oxidizing/reducing reaction or a diazotization/coupling reaction.

How does azo dyes produce color?

Since anilines are prepared from nitro compounds, some azo dyes are produced by partial reduction of aromatic nitro compounds. Many azo dyes are produced by reactions from pre-existing azo compounds. Typical reactions include metal complexation and acylation.

What is colorant in textile?

Definition. Textile colorants impart color to a textile material, usually with a high degree of permanency, as a result of their chemical binding or physical entrapment within or around the textile material.

What is used as colorant?

Colorants are used in many industries – to colour clothes, paints, plastics, photographs, prints, and ceramics. Pigments are insoluble compounds used in paints, printing inks, ceramics and plastics. They are applied by using a dispersion in a suitable medium. Most pigments used are also organic compounds.

Is azo dye and Azoic dye same?

Azo dyes are also known as azoic or nepthol dyes. The azo dyes are chiefly of red, brown and yellow colors. Dyes used in the food and textile industry consist of 60-70% of azo dyes. They are synthetic colors and most of them contain only one azo group.

Which dyes are azo dyes?

Pages in category “Azo dyes”

• Acid orange 5.
• Acid Orange 7.
• Acid orange 19.
• Acid Red 13.
• Acid red 88.
• Alcian yellow.
• Alizarine Yellow R.
• Allura Red AC.

What colors are azo dyes?

3.2 Food azo dyes. Azo dyes are the largest group of artificial food dyes, including 70% of the organic dyes generated in the world. Moreover, the commonest azo dyes in the food industry have been considered to be the yellow dyes (sunset yellow and tartrazine) and red dyes (azorubine, ponceau, amaranth, and allura red) …

How is azo dyes detected?

The use of planar chromatography and mass spectrometry can be really helpful in confirming the identity of the azo dyes, offering highly relevant molecular information of the responsible compounds in the fabrics.

What happens to the azo linkage of azo dye?

The azo linkage is the most labile portion of an azo dye molecule and may easily undergo enzymatic breakdown in mammals, including man. The azo linkage may be reduced and cleaved, resulting in the splitting of the molecule in two parts. This reaction is carried out by an enzyme named azo-reductase.

What is the most labile part of azo dye?

The azo linkage is the most labile portion of an azo dye molecule and may easily undergo enzymatic breakdown in mammals, including man. The azo linkage may be reduced and cleaved, resulting in the splitting of the molecule in two parts.

What are aromatic azo dyes?

Aromatic azo compounds (R = R’ = aromatic) are usually stable and tend to produce strong vivid colours. The general formula for making an azo dye requires two organic compounds- a coupling component and a diazo component.

What is the LD50 of azo dyes?

The majority of azo dyes (food and textile) have LD50 values between 250-2,000 mg/kg body weight, indicating that for a lethal dose many grams of azo dyes have to be consumed in a singe dose. As azo dyes are highly water soluble, they do not accumulate in the body, but are metabolised in the liver and excreted in the urine.