SYNTHESIS OF MONOAZO PIGMENTS BASED ON -NAPHTHOL AND ACETOACETANILIDES AND THEIR APPLICATIONS
SYNTHESIS OF MONOAZO PIGMENTS BASED ON -NAPHTHOL AND ACETOACETANILIDES AND THEIR APPLICATIONS
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Date
2006-10
Authors
YAKUBU, YUSUF
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Abstract
Aniline, m-toluidine, o-nitroaniline, 4-nitroaniline and 2,4-dinitroaniline were used
to synthesize twelve pigments based on -naphthol, acetoacetanilide and
acetoacet-2,5-dichloroaniline coupling components using the general principle of
diazotisation and coupling. The amount of diazo components and coupling
components used for synthesis is directly proportional to the yield of the resultant
pigment but has no effect on the pigments properties. Most of the synthesized
pigments with the exception of pigment derived from 2,4-dinitroaniline and -
naphthol did not recrystallise fully in glacial acetic acid and none at all
recrystallised from xylene, benzene or toluene. However, a few of the pigments
partially recrystallised in 2-ethoxyethanol.
Visible absorption measurements of the pigments were determined. The results
indicated that among the pigments (A, D, G, J) synthesized using -naphthol,
pigment A had the lowest λmax (449.3nm) while J absorbed maximally at λmax
(498.5nm). For pigments B, E, H, K and M synthesized using Acetoacetanilide,
the highest λmax was indicated by H λmax (478.5nm) and M gave the lowest
λmax(439.6nm).
The use of Acetoacet-2,5-dichloroaniline as coupling agent for pigments
C, F, I indicated similar pattern of absorbance compared to those synthesized
from -naphthol and acetoacetanilide with F having the lowest λmax(432.5nm).
The pigments were applied to cotton, polyester, wool, cotton/polyester blend and
paper, after which their fastness properties were investigated.
It was found that the presence of an electron donating group (-NH2,-CH3 etc)
positioned on the ortho, meta, or para position of the electron withdrawing (-NO2)
group on the arylamine imparted reasonably on the resonance of the pigments.
The analysis of the results indicated that pigments synthesized based on -
naphthol are better applied on cotton, polyester and cotton/polyester blend while
the acetoacetarylide-based pigments are more useful on wool and paper. In
virtually all cases, the pad-bake method of application gave better result than the
resin-bond-bake method.
On general account the pigments had good fastness to washing while light
fastness was only moderate.
Description
Being a thesis submitted to the postgraduate school in partial fulfillment of
the requirements for the award of Master of Science (M.Sc) Degree in
Textile Science and Technology, Ahmadu Bello University, Zaria.
Department of Textile Science and Technology,
Faculty of Science,
Ahmadu Bello University,
Zaria.
Keywords
SYNTHESIS,, MONOAZO,, PIGMENTS,, BASED,, -NAPHTHOL,, ACETOACETANILIDES,, APPLICATIONS