Thesis Abstract

<p> Highly electros withdrawing groups, bromine and oyano, were<br>substituted into 2′ , and 6′ – positions in the acceptor ring of<br>azo dyes, with condenesable aldehyde group in the 4-position. The<br>formyl group of the resulting dyes were condensed with active<br>methylene compounds to give series of dyes. Characterisation and<br>spectrophotometry analysis of the derived dyes were carried out.<br>The dyes were applied to polyester and their dyeing properties<br>were investigated.<br>It was found that the incorporation of these highly electron<br>withdrawing groups led only to slight bathochromic shifts of<br>visible absorption bands. Seasons such as steric interference<br>were given to explain the effect. However, it was found that the<br>dyes derived from 2′,6′-dicyano para-aminoaeompounds were more<br>bathochromic than their 2′,6′-dibromo para-aminoazo conterparts.<br>Most of the dyes exhibit, negative halochromism due to the.<br>effect of electron withdrawing groups incorporated in the<br>acceptor ring. Most of the. dyes also show bathochromic shifts as<br>the solvent polarity was increased.<br>The dyes are generally fast to washing but very poor to<br>light. <br></p>

Thesis Overview