THE EFFECTS OF INCORPORATING HIGHLY ELECTRON WITHDRAWING GROUPS ON COLOUR AND DYEING PROPERTIES OF MONO AZO DISPERSE DYES

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Date
1992-12
Authors
YAKUBU, Mohammad Kabir
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Abstract
Highly electros withdrawing groups, bromine and oyano, were substituted into 2' , and 6' - positions in the acceptor ring of azo dyes, with condenesable aldehyde group in the 4-position. The formyl group of the resulting dyes were condensed with active methylene compounds to give series of dyes. Characterisation and spectrophotometry analysis of the derived dyes were carried out. The dyes were applied to polyester and their dyeing properties were investigated. It was found that the incorporation of these highly electron withdrawing groups led only to slight bathochromic shifts of visible absorption bands. Seasons such as steric interference were given to explain the effect. However, it was found that the dyes derived from 2',6'-dicyano para-aminoaeompounds were more bathochromic than their 2',6'-dibromo para-aminoazo conterparts. Most of the dyes exhibit, negative halochromism due to the. effect of electron withdrawing groups incorporated in the acceptor ring. Most of the. dyes also show bathochromic shifts as the solvent polarity was increased. The dyes are generally fast to washing but very poor to light.
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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. December, 1992
Keywords
EFFECTS,, INCORPORATING,, HIGHLY,, ELECTRON,, WITHDRAWING GROUPS,, COLOUR,, DYEING PROPERTIES,, MONO AZO,, DISPERSE DYES.
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