dying of fabric class 12th chemistry project

3. A C K N O W L E D G E M E N T
I would like to express a deep sense of thanks &
gratitude to my project guide Miss Amneet for
guiding me immensely through the course of the
project. She always evinced keen interest in my
work. Her constructive advice & constant motivation
have been responsible for the successful completion
of this project. I also thanks to my parents for their
motivation & support. I must thanks to my classmates
for their timely help & support for compilation of this
project. Last but not the least; I would like to thank
all those who had Helped directly or indirectly
towards the completion of this project.

4. Plastic toys for children to that fabrics you wear, from food to
wood; hardly there is any industry where colouring material that
colour commodities of our day to day use. Dyes are applied
everywhere, from a natural or synthetic substance used to add a
colour or to change the colour of something. Dyes are the dyes
are not used commercially.
A dye is a coloured substance that has an affinity to the
substrate to which it is being applied. It is an Ionising and
aromatic organic compounds. The dye is generally applied in an
aqueous solution, and may require a mordant to improve the
fastness of the dye on the fiber. With the help of dyes we can
easily manipulate things according to our liking. At the very
basic level the use of color in identifying individual components
of tissue sections can be accomplished primarily with dyes. Dyes
are applied to numerous substrates for example to textiles,
leather, plastic, paper, food etc.
The rule that we apply to other chemicals is similarly applicable
to dyes also. They also get completely or atleast partially soluble
in which it is being put to. For example certain kind of dyes can

5. be toxic, carcinogenic or mutagenic and can be hazardous to
health.
Dyes are basically ionising and aromatic compounds, they have
Chromophores present in them. Their structures have Aryl rings
that has delocalised electron systems. These structures are said
to be responsible for the absorption of electromagnetic radiation
that has varying wave lengths, based upon the energy of the
electron clouds.
Chomophores make the dyes proficient in their ability to absorb
radiation. Chromophores act by making energy changes in the
delocalised electron cloud of the dye. This alteration invariably
results in the compound absorbing radiation within the visible
range of colors and not outside it. Human eyes detects this
absorption, and responds to the colors.
Electrons may result in loss of color, their removal may cause
the rest of the electrons to revert to the local orbits. A very
good example is the Schiff's reagent. As Sulphurous acid reacts
with Pararosanilin, what happens is that a Sulphonic group
attaches itself to the compound's central carbon atom. This
hampers the conjugated double bond system of the Quinoid ring,
and causes the electrons to become localised. As a consequence
the ring ceases to be a Chromophore. As a result, the dye

6. becomes colourless.To conclude chromophores are the atomic
configurations which has delocalised electrons. Generally they
are represented as carbon, nitrogen, oxygen and sulphur. They
can have alternate single and double bonds.
Auxochrome, the only substance responsible for providing
solubility and cohesiveness to dyes. An auxochrome is a group of
atoms attached to a chromophore which modifies the ability of
that chromophore to absorb light. Examples include the hydroxyl
group (-OH), the amino group (-NH2), and an aldehyde group (-
CHO). The presence of an auxochrome in
the chromogen molecule is essential to make a dye. However, if
an auxochrome is present in the meta position to the
chromophore, it does not affect the color.
Auxochrome has the ability to intensify colors. It is a group of
atoms which attaches to non- ionising compounds yet has the
ability to ionise. Auxochromes are of two types, positively
charged or negatively charged.

7. Dyes can be classified in several ways, each class has a very
unique chemistry, structure and particular way of bonding. Some
dyes can react chemically with the substrates forming strong
bonds in the process, and others can be held by physical forces.
Some of the prominent ways of classification are given below
 Natural / Synthetic
 Organic / Inorganic
 By area and method of application
 Chemical classification - Based on the nature of their
respective chromophores.
 By nature of the Electronic Excitation
 According to the dyeing methods
 Anionic (for Protein fibre)
 Direct (Cellulose)
 Disperse (Polyamide fibres)
US International Trade Commission has advocated the most
popular classification of dyes.
This system classifies dyes into 12 types, which are given below:
Group Application
Direct Cotton, cellulosic and blended
fibres
Vat dyes Cotton, cellulosic and blended

8. fibres
Sulphur Cotton, cellulosic fibre
Organic pigments Cotton, cellulosic, blended
fabric, paper
Reactive Cellulosic fibre and fabric
Disperse dyes Synthetic fibres
Acid Dyes Wool, silk, paper, synthetic
fibres, leather
Azoic Printing Inks and Pigments
Basic Silk, wool, cotton
The Dyes are classified based on the products to which they can
be applied and the chemical nature of each dye. Dyes are
complex unsaturated aromatic having characteristics like
solubility, intense color, sub-stansiveness and fastness. A dye-
formulation is supposed to have approximately 10-80% pure
dyestuff. It is mostly observed that dyestuffs delivered in
powder form have a higher value. While a lower value is obtained
for the liquid formulations.

9. Alternative titles: aniline green; benzaldehyde green; china green
Malachite green, also called aniline green, benzaldehyde green,
or china green, triphenylmethane dye used medicinally in dilute
solution as a local antiseptic. Malachite green is effective
against fungi and gram-positive bacteria. In the fish-breeding
industry it has been used to control the fungus Saprolegnia, a
water mold that kills the eggs and young fry. Malachite green
also is used as a direct dye for silk, wool, jute, and leather and
to dye cotton that has been mordanted with tannin. Prepared
from benzaldehyde and dimethylaniline, the dye occurs as
lustrous green crystals soluble in water and in alcohol.

10. APPARATUS REQUIRED:
 Test tube
 Water bath
 Flask  Beaker
 Watch glass
 China dish
CHEMICAL REQUIRED:
 3 ml of benzaldehyde
 6 ml of dimethylaniline
 3 g of Anhydrous ZnCl2
 2 g of PbO2
 4 g of sodium sulphate in cold water
PROCEDURE:
1. Place 3 g of an hydrous ZnCl2 in a china dish and 3 ml of
benzaldehyde and 6ml of dimethylaniline to it.
2. Cover it with watch glass and heat for about 90 minute on a
water bath. Stir frequently and if the mixture becomes very
viscous to stir, add 1 ml of hot water.
3. While the china dish is still on the water bath, add 5 ml of
water, stir the contents with a glass rod to dissolve the
maximum dye and transfer the solution to 400ml beaker.

11. 4. Add 125 ml of ice cold water. Leuco form of
the dye is obtained. With stirring, now add a suspension of 2g
PbO2 in 20 ml of water and then 4 g of sodium sulphate in 20
ml of water to it. Warm and filter.
OBSERVATION:
A dark green dye is obtained.
USES
Malachite green is traditionally used as a dye. Millions of
kilograms of MG and related triarylmethane dyes are produced
annually for this purpose.
[3] MG is active against the protozoan Saprolegnia, which
infects fish eggs in commercial aquaculture, MG is used to treat
parasites and is used as an antibacterial. It is a very popular
treatment against Ichthyophthirius multifiliis in freshwater
aquaria. The principal metabolite, LMG, is found in fish treated
with malachite green, and this finding is the basis of controversy
and government regulation. See also Antimicrobials in
aquaculture.
MG has frequently been used to catch thieves and pilferers.
The bait, usually money, is sprinkled with the anhydrous powder.
Anyone handling the contaminated money will find that on upon
washing the hands, a green stain on the skin that lasts for
several days will result.

12. APPARATUS REQUIRED:
 Test tube
 Weighing balance
 Burner
 Conical flask
CHEMICALS REQUIRED:
 2g Resorcinol
 2g Phthalic anhydride
 5% NaOH
 2ml Conc. H2SO4
PROCEDURE:
1. Take 2g Resorcinol and 2g Phthalic anhydride and add 2ml
conc. H2SO4 to it.
2. Heat the content on burner till the content turns black.
3. Cool the contents and add 20 ml of 5% NaOH in a conical
flask.
4. Vary concentration of NaOH and water to obtain different
intensities of colour.

13. OBSERVATION:
The dye formed shows fluorescence. It appears green from
some angle and orangish yellow from others. The dye when put
in sink with a large amount of water turned into bright yellow
colour.

14. BIBLIOGRAPHY
 NCERT books
 www.google.co.in
 www.wikipedia.org