Synthesis, properties and colour assessment of some new 5-(3-and 4-substituted phenylazo)-4,6-dimethyl-3-cyano-2-pyridones

A series of 5-(3- and 4-substituted phenylazo)-4,6-dimethyl-3-cyano-2-pyridones were synthesized, starting from acetylacetone and arenediazonium salt, followed by condensation with cyanoacetamide using a modified literature procedure. The experimental investigation included modification of the synthetic procedure in terms of solvent, temperature, isolation techniques as well as purification and identification of the products. The azo dyes were characterized by melting point, IR, UV/Vis, H-1 NMR and MS data. HPLC analyses were also performed. The 2-hydroxypyridine/2 -pyridone tautomeric equilibration was found to depend on the polarity of the applied solvents. A colour assessment of the solid dyes and dyed polyester fabrics was also performed and the correlation between the colour and the Structure of the dyes is discussed.