What is an Azo Dye?
Azo dyes are organic compounds that belong to the functional group (N=N). These are one of the most critical colourants in the textile industry. Azo dyes are also known as ice or magic colours, as they need a shallow temperature. These are used for several purposes, including colouring foods, candies, cosmetics, and beverages. These are available in different forms. One of the most significant subgroups of synthetic dyes is these azo dyes. Because aromatic rings are present, these dyes are highly coloured dyes.
History of Azo Dyes
Azo Dyes have been used for the past few years. Direct Azo dyes are the easiest to apply. These direct dyes contain the chemical components that make them water soluble and can be easily absorbed by different materials. In 1884, the first Azo dye, Congo red, was used, which is now replaced by other chemically synthesized dyes that are more resistant to light and heat.
Chromium and copper are the most common metals used in these dyes. Different metals are used to alter the properties of these dyes and make them suitable for various purposes. These pocket-friendly, long-lasting, and eco-friendly dyes are the best dyes with a wide variety of choices for several industries.
Synthesis of Azo Dyes
Various reactions of Naphthylamines and Naphthols are combined to produce these dyes. These dyes are made in the following two steps:
- Synthesis of aromatic diazonium ions from an aniline derivative.
- Diazonium salt is coupled with an aromatic compound.
What are Azo Dyes used for?
Azo dyes have a variety of uses and are used by multiple industries.
- These are widely used in the pharmaceutical industry for adding colour to medical types of equipment.
- These dyes play a major role in the cosmetic industry.
- The textile industry uses the Azo dyes to create different shades and add colour to different materials and fabrics.
- These can be used as complexometric indicators as these undergo a colour change in the presence of metal ions.
- Azo Dyes are used as medicine to treat insomnia.
- Thermal transfer printers also use the Azo dyes.
- Azo Dyes are great food colourants. Tartrazine is a lemon-yellow colour azo dye used to add colour to food.
Features of the Dye
- They possess a high fastness ability.
- These are used to dye the cellulosic material.
- Coupling these dyes is necessary for producing good colours. And coupling is done in an alkaline solution.
- It has admirable bright shades.
- The final colour of the dye is produced after immersing the material for a few seconds. Therefore, it has a fast application.
- These dyes are suitable for small-scale industries.
- Azo Dyes are effective and less expensive.
- The dye’s environmental impact is low, making it a safe option.
- It has a wide range of colour options.
- These dyes are insoluble in water.
These dyes are often produced by developing countries to cater to the growing demand and add variety to several market products.