Basic dyes and associated auxiliaries

1. BAHIR DAR UNIVERSITY
Ethiopian Institute of Textile and
Fashion Technology
“Dyes and Auxiliaries”
Seminar on “Chemistry of Auxiliaries
Associated With Basic Dyes”
Prepared By:- Berihun Gashu (MSc in TC)
Submitted to:- Mr. Tamene W.
(Asst. Prof.)
Febu. 2021 G.C.
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2. Out line
o Introduction
o Chemistry of auxiliaries associated
with basic dye
o Summery
o References
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3. Are basic dyes positively charged?
Basic dye are called cationic dyes because the chromophore in
dyes molecules contains a positive charge.
Basic dyes molecules contains positive charge and materials have
negative charge this is the reason dyeing is properly done.
 It is powerful coloring agent.
Basic
dyes
Introduction
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4. What properties basic dyes
have?
Synthetic dye class
Ionic Nature : cationic
Shade range :unlimited shade range with high
tinctorial value ,brightness
Solubility : soluble in water
 Leveling Properties : poor leveling
Affinity : very affinity towards wool , silk and acrylic 4

5. Chemical structures of some typical basic dyes
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6. Limitation of basic
dyes?
o Poor light fastness.
o Shade value is not good.
o Skin problems and health
issues occur.
o Not good affinity for
cellulosic fibers.
o Normal substantivity.
o Wide shade range.
o Better brightness on the
surface of materials or
fabric.
o Good tinetorial value
Advantage of basic dye?
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7. Applications
 These dyes are applied to
o Wool ,
o Silk and
o Acrylic fiber.
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8. Auxiliary
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9. What are Essential Auxiliaries Associated With
Basic/ Cationic Dye?
o Wetting Agent
o Acetic Acid
o Sequestration or Chelation
o Leveling Agent/ Retarding
Agent
o Electrolyte
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10. Wetting agents
Wetting agents are substances that reduce the surface tension of
water to allow it to spread drops onto a surface, increasing the
spreading abilities of a liquid.
Lowering the surface tension lowers the energy required to
spread drops onto a film, thus weakening the of the liquid and
strengthening its adhesive properties.
One principle of how wetting agents work is in the formation of
micelles.
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11. Types of wetting
agents
There are four main types of wetting agents
 Anionic, cationic, and amphoteric wetting agents ionize when mixed with
water.
Anions have a negative charge, while cations have a positive
charge.
Amphoteric wetting agents can act as either anions or cations,
depending on the acidity of the solution.
Nonionic wetting agents do not ionize in water.
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12. Acetic Acid
Acetic acid used for maintain PH 4.5-5.5, because the basic dye
require acidic medium.
Acetic acid (CH3COOH), also called ethanoic acid, the most
important of the carboxylic acids.
Industrially, acetic acid is used in the preparation of metal
acetates, used in some printing processes; vinyl acetate,
employed in the production of plastics; cellulose acetate, used
in making photographic films and textiles; and volatile organic
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13. Acetic acid has been prepared on an industrial scale by air
oxidation of acetaldehyde, by oxidation of ethanol (ethyl
alcohol), and by oxidation of butane and butene.
Cont.…
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Where: Rh, rhodium
I, iodide

14. Sequestrating or
Chelating
A sequestering or chelating agent is a complex forming auxiliary
chemical with metals such as Iron, Copper, Nickel, Zinc and
Magnesium that are present in water and affects the textile
processing in many way.
It is a dyeing auxiliaries which is used during dyeing for removing
hardness of water.
They form molecules in which the ions are held so securely
(sequestered) that they can no longer react.
Aminopolycarboxylates(EDTA), phosphates and phosphonates,
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15. EDTA
Good sequestering agent for calcium and magnesium at alkaline
pH but no sequestering agents on Fe3+ at alkaline pH.
Not stable with oxidizing agents and Low solubility in acidic
medium.
Some ligands can bond to a metal atom using more than two
pairs of electrons.
 An example is ethylenediamminetetraacetate ion (EDTA4-), the
Lewis structure of which is shown below. 15
Cont.…

16. 16
Cont.…

17. Retarding
Effect
To solve problem of dyeing on acrylic fibers various approaches
have been developed including the use of temperature as well as
cationic and anionic retarders.
There are two types of retarding agents:-
(a) those that form a complex with the dye and thus tend to
retain it in the dye bath.
(b) those that compete with the dye for the ionic dye sites in
Retarding Agent
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18. A cationic retarder based on a quaternary ammonium compound
competes with the cationic dye for the anionic dye sites in the fiber.
This competition reduces the initial strike rate of the dye, to promote
level dyeing, but may also reduce the final dye bath exhaustion.
Generally speaking, the two fundamental mechanisms that contribute
contribute to level dyeing are
o Control of exhaustion of dye so that it is taken up evenly
Cont.…
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19. Containing long aliphatic chains.
They act by reducing the effective dye concentration in the bath at
higher temperatures, the dye cations replacing the retarder cations due
to their strong affinity.
The multiple positive charges of the polymeric film barrier, formed
around the fiber surface, greatly reduce the rate of dye adsorption.
As the temperature increases, this barrier film breaks down and allows
Quaternary Ammonium
Compound
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20. Quaternary ammonium compounds are prepared by the alkylation of
tertiary amines with a halocarbon.
The quaternization reaction can be used to produce a compound with
unequal alkyl chain lengths; for example when making cationic
surfactants one of the alkyl groups on the amine is typically longer than
the others.
Menshutkin reaction
Quaternization
Cont.…
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X, a halide but
sometimes a sulfate ion

21. Substituents in quaternary ammonium compound
Cont.…
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22. Cont.…
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23. Retarder has a compatibility value equal to or slightly lower than that
of the dyes, so that it will tend to be absorbed by the fiber either at the
same rate as the dyes or somewhat more quickly.
If the compatibility value of the retarder is significantly lower than that
of the dyes, then there is a very real tendency for it to act as a blocking
agent (with attendant problems), whilst if its compatibility value is
much higher its efficacy is reduced.
Cont.…
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24. A useful general classification of cationic retarders according to their
properties has been given:
(a) strongly cationic with a strong blocking effect
(b) moderately cationic with a weak blocking effect
(c) weakly cationic with no blocking effect
(d) products with little or no retarding effect but giving some levelling
Cont.…
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25. Polyacrylamide (IUPAC poly(2-propenamide) or poly(1-
carbanoylethylene), abbreviated as PAM) is a polymer (-
CH2CHCONH2-) formed from acrylamide subunits.
It is highly water-absorbent, forming a soft gel when hydrated,
used in such applications as polyacrylamide gel electrophoresis.
In the straight-chain form, it is also used as a thickener and
Polyacrylamide
s
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 Gel electrophoresis is a method for separation and analysis of
macromolecules (DNA, RNA and proteins) and their fragments, based
on their size and charge.

26. Reaction
Cont.…
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27. Polyacrylamides of molecular mass 2500–780 000 have been
evaluated more recently.
These agents, because of their large molecular size, do not diffuse
into the fiber but are strongly adsorbed at the fiber surface, reducing
its anionic potential.
They retard the dyeing rate far more than does an equal
concentration of a conventional quaternary agent, but do not assist
Cont.…
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28. Electrolytes such as sodium chloride and sodium sulphate tend to
retard dyeing through preferential adsorption and subsequent
displacement by the dye of the more mobile sodium ions, although
the effect is relatively weak even compared with the weaker cationic
retarders.
Nevertheless, the use of up to 10% o.w.f. sodium sulphate in
combination with a cationic retarder may enable the amount of the
Electrolytes
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29. The limitations of electrolytes, apart from this lower effectiveness, are
that they reduce the final uptake of dye, their effectiveness decreases
with increase in temperature and their effect is greatest with fibers
fibers containing weakly anionic groups such as carboxylate, rather
than stronger ones such as sulphonate.
The retarding effect of electrolytes in the application of basic dyes to
acrylic fibers increases with increasing concentration of salt up to a
to a certain level.
Cont.…
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30. These results have led to the conclusion that ionic mechanisms alone
do not entirely explain the complex interactions that occur between
basic dyes and acrylic fibers.
Hydrophobic interaction also plays an important part and it has been
demonstrated that multivalent anions such as sulphate or phosphate
can enhance the hydrophobic interaction, thereby also increasing dye
sorption in some circumstances.
Whilst such results are of interest in terms of dyeing theory, it is
Cont.…
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31. The effect of salt on the equilibrium sorption of basic dyes on
acrylic fibers
Cont.…
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32. Summery
Basic dyes contains positive charge and materials have
negative charge this helps to have proper dyeing process, it is
powerful coloring agent. Basically cationic dye uses different
auxiliaries either for leveling agent or retarding reaction site of
dyes or fibers, wetting agent and buffering agents or keeping
the medium of solution. Cationic dyes are applicable for wool,
silk and acrylic fibers.
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33. Referen
ce
Colorants and auxiliaries ORGANIC CHEMISTRY AND APPLICATION
PROPERTIES Second Edition Volume 2 – Auxiliaries
The retarding action of polyacrylamide in acrylic dyeing by S R
Shukla and Manisha Mathur (2008)
https://en.wikipedia.org/wiki/Quaternary_ammonium_cation#S
ynthesis
Antifouling Activity of Synthetic Alkylpyridinium Polymers Using
the Barnacle Model Veronica Piazza 1 , Ivanka Dragić 2 , Kristina
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34. Petrucci, Ralph H., et al. General Chemistry: Principles and Modern
Applications. Upper Saddle River, NJ: Prentice Hall, 2007
https://nptel.ac.in/content/storage2/courses/116104046/29.pdf
https://textilesgreen.in/basic-dye/
https://en.wikipedia.org/wiki/Menshutkin_reaction
https://en.wikipedia.org/wiki/File:Resonance-imidazole.svg
https://en.wikipedia.org/wiki/Ethylenediaminetetraacetic_acid#Synth
esis
Cont.…
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35. Kirchner, S.; Gyarfas, Eleonora C. (1957). Barium
(Ethylenediaminetetracetato) Cobalt(III) 4-Hydrate. Inorganic
Syntheses. 5. pp. 186–
188. doi:10.1002/9780470132364.ch52. ISBN 9780470132364.
Dyeing of Cotton Fabric with Basic Dye in Conventional Method
and Pretreated with Cationic Polyacrylamide Syed Atiqur
Rahman* and A. B. M. Foisal
https://www.chemicalbook.com/ChemicalProductProperty_EN_
Cont.…
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36. Thank you for staying
with my presentation!
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