Synthesis, Structure Investigation and Dyeing Assessment of Novel Bisazo Disperse Dyes Derived from 3-(2'-Hydroxyphenyl)-1-phenyl-2-pyrazolin-5-ones

Abstract

In an attempt to find a new class of bisazo disperse dyes with better dyeing properties, a series of novel bisazo dyestuffs based on 4-arylhydrazono-3-(2'-hydroxyphenyl)-1-phenyl-2-pyrazolin-5-ones <TEX>$\mathbf{3a-f}$</TEX> were prepared by diazocoupling of p-nitrophenyl diazonium chloride with 4-arylhydrazono-3-(2'-hydroxyphenyl)-1-phenyl-2-pyrazolin-5-ones <TEX>$\mathbf{2a-f}$</TEX>. Compounds <TEX>$\mathbf{3a-f}$</TEX> were subsequently reacted with acetic anhydride in the presence of p-toluenesulfonic acid afford the corresponding O-acetyl derivatives <TEX>$\mathbf{4a-f}$</TEX>. The latter products as well as spectral data indicated that compounds <TEX>$\mathbf{3a-f}$</TEX> exist predominantly in the azo-hydrazone tautomeric form (H) as the ZE-configuration. Additionally, two series of the synthesized dyes <TEX>$\mathbf{3a-f}$</TEX> and <TEX>$\mathbf{4a-f}$</TEX> were applied as disperse dyes for dyeing polyester fabrics and their fastness properties were evaluated. Also the position of color in CIELAB coordinates (<TEX>$L^*$</TEX>, <TEX>$a^*$</TEX>, <TEX>$b^*$</TEX>, <TEX>$H^*$</TEX>, <TEX>$C^*$</TEX>*) was assessed.