Dyes are colored organic compounds used to impart color to materials like textiles, paper, leather, and plastics. They are classified based on their source, chemical structure, and application method. Natural dyes come from plants, fungi, lichens, and minerals while synthetic dyes are manufactured. Dyes are also grouped by their chromophores - the part of the molecule responsible for color. Common chromophores include azo, nitro, and indigo groups. Finally, dyes can be classified by how they are applied to materials like direct dyes, mordant dyes, vat dyes, dispersive dyes, and reactive dyes. Each application method requires different dye properties and fiber treatment.

1. Dyes
Presented By
SHUBHANGI V. MESHRAM
M.Sc CHEMISTRY 4th SEM
G H RAISONI SCHOOL OF SCIENCE

2. Contents
1.Introduction of Dyes
2.Properties of Dyes
3.Classification of Dyes

3. INTRODUCTION
DYES
Dye is a coloured organic compounds that are used to impart colour to
various substrates, including paper, leather, fur, hair, drugs cosmetics, plastic,
waxes, and textile materials, etc.
A dye is a coloured compound, normally used in solution, which is
capable of being fixed to fabric.

4. Properties of Dyes
Dyes must posses the following four properties:-
1. Colour
2. Solubility in water
3. Substantivity or Reactivity
4. Abilty to withstand washing, dry, cleaning and exposure to light.
The dye has a colour due to the presence of chromophore and its
fixed property to the acid or basic groups such as OH, SO3H, NH2, NR2,
etc.
The polar auxochromes makes the dye water- soluble and binds the dye
to the fabric.

5. Classification of Dyes
Dyes are classified based on their origin, chemical properties, and application.
1. Based on the source of materials.
2. Based on the chemical structure [chromophores]
3. Based on method of application

6. 1. Natural Dyes
● Natural dyes are dyes or colorants derived from
plants,invertebrates, or minerals
● The majority of natural dyes are dyes vegetables dyes from plant
source. E.g:- roots, berries, leaves and wood.
● Other organic source include fungi and lichens
1. Classification based on the source of materials

7. 2. Synthetic Dyes
● Synthetic Dyes are manufactured from organic molecules.
● Almost all the colours that we see today are synthetic dyes.
● Synthetic dyes are used everywhere in everything.
● This is because of they are cheaper to produce, brighter, more colour fast , and
easy to apply fabric.
● E.g- Acid Dyes, Azo Dyes, Basic Dyes, Mordrant dyes, etc.

8. 2.Classification based on their structure[chromophores]
Chemical constitution of dyes are so varied.
1. Nitro and Nitroso Dyes
2. Azo Dyes
3. Indigo Dyes
Other classes : azoic, xanthene, quinoline oxazine,etc

9. 1. Nitro and Nitroso Dyes
Nitro Dyes: These dyes contain nitro [-NO2] and hydroxy group[OH]as
auxochrome.
E.g. Napthol yellow S
Nitroso Dyes: nitroso groups [-NO] as the chomophores and phenolics -OH
as auxochrome
E.g Gambine Y

10. 2. Azo Dyes
● Azo group [-N=N-] is a present as primary chromophore in their
molecular structure which is presenet between two aromatic rings.
● Largest used dyes 2/3 of the dyes used are azo dyes.
● e.g . Tartrazine, Congo Red, Methyl orange, Chrysoidine

11. 3. Indigo Dyes
● Indigo dyes have carbonyl chromophore and indigoid structure
[-CO=C=C-CO]
● Used to dye cotton yarn, which is mainly used for the production of denim
cloth or blue jeans
● E.g Indigo

12. 3.Classification methods of application
Methods used for application depends on the nature of both dyes and fabrics. They are
classified on the basis of technique employed for their application.
● Direct Dyes
● Mordant dyes
● Vat dyes
● Dispersive Dyes
● Reactive Dyes

13. Direct Dyes
● Applied directly
● Carried out in a neutral or slightly alkaline dye solution.
● It contains acidic or basic auxochrome.
● Polar in nature
● Have high affinities for cellulosic fibers.
● Used on cotton, paper, leather, wool, silk, and nylon.
● E.g- martius yellow

14. Mordant Dyes:-
No natural affinity towards textile fibers are attached with the fiber with the
help of mordrant are known as mordrant dyes.
● Alum [aluminium potassium sulfate] this is most widely used modrant.
And chrome [potassium dichromate] brighters dye colours and is most
commonly used with wool than any fibers.
● Fiber is first treated with modrant and with dye solution.
● Most suitable for wool and nylon.
● E.g - Alizarin

15. ● insoluble in water.
● Soluble in sodium hydrosulfide[Na-S-H] great affinity for cotton and
fibers.
● E.g Indigo Dyes is a good example of vat dyes.
Vat Dyes:-

16. Dispersive Dyes
● Dispers dyes is a class of non- ionic dye, which has low water solubility
and exist in water primarily in a highly dispersed.
● It is mainly used for dyeing polyester fibers, nylon, orlon, and cellulose
acetate.
● Insoluble and partial Water soluble dyes.
● E.g Duranol Red2B

17. Reactive dyes
● Reactive dyes are cationic dyes, which are used for dyeing cellulose,
protein and polyamide fibers.
● Reactive dyes are found in powder, liquid and paste form.
● Reactive dyes are soluble in water.
● Dyeing method of reactive dyes is easy.
● It requires less time and low temperature for dyeing.
● High purity reactive dyes are used in the ink jet printing of textiles,
specially cotton.

18. Thank you