Kinetics of destruction of acid and mordant dyes in Fenton reaction was investigated by the use of spectral method. Inhibition of destruction of some mordant dyes was observed. A simple theory for describing this phenomenon was proposed, which is based on consideration of participation of iron ions in complex formation with mordant dye ligands. By the use of chemical software JChem (ChemAxon) it was found that mordant dye exhibiting stability in Fenton solution bears hydroxyl group with high dissociation constant, pK=2,57. On the contrary, another dye bearing hydroxyl with low dissociation constant, pK1=6,65, does not exhibit any inhibition in oxidation process. UV-Vis spectral studies of the complexes of several mordant dyes prove correlations with their stability in Fenton reaction, however some dyes exhibit no relationship of this kind.

Systematic analysis of quantitative structure – property relationships for dyes of different nature has been reviewed. On the basis of the experimental results published in the literature and theoretical evaluation of amphiphilic and electrophilic properties of dyes of different nature several basic conclusions of scientific and practical importance are proposed. It was found that water/octanol partition coefficients exhibit correlation with dye partition between hydrophobic synthetic fibres and dyebath as well as dye affinity. Hydrophobicity of dyes controls several technical properties of dyes and dyeings, such as wash fastness and light fastness, migration factor, rate of dyeing and fixation rate. Energy of frontier electronic orbitals (HOMO and LUMO energies) correlates with different properties characterizing redox properties of dyes: oxidative and reductive destruction in chemical reactions, photochemical and biochemical destruction of dyes, wash and light fastness of dyeings. The results of this study are useful for physico-chemical analysis of dye sorption by textile fibres, destruction of dyes in polymers and solutions as well as for design of new dyes of high quality.