Synthesis, Tautomeric Structure, Dyeing Characteristics, and Antimicrobial Activity of Novel 4-(2-Arylazophenyl)-3-(2-hydroxyphenyl)-1-phenyl-2-pyrazolin-5-ones

Abstract

ABSTRACT. Novel azopyrazolin-5-one dyes 4a-f were synthesized by the regioselective reaction of phenylhydrazine with 2,3,4-chromantrione-3-arylhydrazones 2a-f. The acid dissociation constants pKa for the series prepared were determined and correlated by the Hammett equation. The results of such correlation together with the spectral data indicated that the studied compounds exist predominantly in the hydrazone keto structure, (D) as the Z-configuration. The dyes were applied to polyester fabrics, affording orange-yellow shades and assessments of their dyeing performance are considered. Further, the compounds 4a-f were screened for their antimicrobial activity against various microorganisms.

Synthesis, Structure Elucidation and Application of Some New Azo Disperse Dyes Derived from 4-Hydroxycoumarin for Dyeing Polyester Fabrics

“…Since it has been deduced that the compounds exist as hydrazone structure, a band due to the C=N linking would be expected in the region 1604-1613 cm -1 [ 5,6]. The prominent band occurs around 1545 cm -1 assigned to the benzene ring C=C skeletal vibration associated with the -NH-N= linkage in the 4-position on the coumarin ring [5]. On the other hand, the stretching vibration of the C arom.…”

“…The fact that the coupling products 4a-k show evidence for intramolecular hydrogen bonding is in favor of hydrazone structure (D), since compounds with structure (C) would not possess this property. Since it has been deduced that the compounds exist as hydrazone structure, a band due to the C=N linking would be expected in the region 1604-1613 cm -1 [ 5,6]. The prominent band occurs around 1545 cm -1 assigned to the benzene ring C=C skeletal vibration associated with the -NH-N= linkage in the 4-position on the coumarin ring [5].…”

“…On the other hand, the stretching vibration of the C arom. -N linkage show band between 1355-1330 cm -1 in their spectra [5].…”

“…These azodyes are very useful as precursors for the synthesis of heterocyclic ring systems, which play an important role in pharmaceutical chemistry and dyestuff industry [5,6]. Another interesting feature of this class lies on its tautomeric behavior which has been studied by several investigators for many years.…”

“…Based on these results, the approach reported here is an extension and a continuation of our interest in the synthesis and elucidation of the tautomeric structures of mono and bisazo dyes which were able to dye polyester fabrics [5,6,[14][15][16]. Thus, this work is aiming to study the synthesis of a series of azo disperse dyes having different substituted groups 4a-k in a trial to provide a better understanding of the prevalent tautomeric structure of the compounds in question.…”