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Organic Chemistry

Dyes And Its Characteristics

Dyes: A coloured substance, which can be applied in solution or dispersion to an element such as textile fibres (cotton, wool, silk, nylon) paper, leather, hairs, fur, plastic materials, wax, a cosmetic base, giving it a coloured appearance. 

Characteristics of Dyes: Suitable colour, fast to light, water and oil. Acid-resistant. 

Dyes are made up of chromophores and auxochromes.

  • Acid Dyes are characterized by the presence of –COOH, -SO3H or phenolic group and the colour lies at its negative ion. Examples: Orange I, Orange II, methyl red etc.
  • Basic Dyes are characterized by the presence of –NH2 group, and the colour of these dyes lies at positive ions. Example: Aniline yellow, butter, yellow, etc.