The Influence of Temperature, pH and the Type of Oxime Isomer on the Stability Constant Values of Some Azo Dyes Formations Between Oximes and the Diazotized Sulfanilic Acid Salt

Abstract

The paper deals with studying the effect of experimental factors on the value
of stability constant (K) of the dyes formed by the reactions of aromatic aldoximes as
2-hydroxy benzaldoxime, 2,4-dihydroxy benzaldoxime and 2-hydroxy-1-
naphthaldoxime with diazotized sulfanilic acid salt.
Experimentally the following three physical parameters are found to be
effective on K as, temperature, pH and type of syn or anti isomer of oxime.
The study includes several topics, one of them is the thermodynamic of dye
formation which prove such process is spontaneous and exothermic. The calculated
thermodynmic quantities change have a negative values of Gibbs free energy and heat
of reaction. They have range average values between 30.1-44.6 and 0.6-59.5 in units
of kJ.mole-1 respectively, depending on the structure of the azo dye formation. The
entropy changes for the complex formation are also mentioned and discussed. The
reaction of azo dye formation is based on donor-acceptor mechanism.