A combined experimental and DFT investigation of mono azo thiobarbituric acid based chalcone disperse dyes

A number of monoazo dyes were synthesized by the reaction of 4-aminoacetophenone with different substituted benzaldehydes to give a new series of chalcone derivatives. The diazonium salts of these chalcones then allowed to react with thiobarbituric acid to produce the appropriate azo dye. The structures of the newly synthesized dyes were assigned by IR, NMR spectral data. IR study confirmed the existence of azo-dioxothioxo tautomer in the solid phase while H-1 NMR study indicated the predominance of azoenol-oxothioxo or hydrazo-dioxothioxo tautomers. The geometries of the azo and hydrazo tautomeric forms and their electronic absorption of the dyes were optimized at B3LYP/6-311G level of theory. All the azo compounds were evaluated for their dyeing performance on polyester fibers, and PET. All the synthesized dyes gave moderate to excellent fastness properties on PET fiber. The effects of the nature of the substituents on the color and dyeing properties of these dyes have been evaluated. The mechanism of dyeing polyester fiber was discussed.

Automated summary

A new series of monoazo dyes were synthesized through reactions of 4-aminoacetophenone with various substituted benzaldehydes, followed by reaction with thiobarbituric acid to produce azo dyes. The structures were confirmed using IR and NMR data. Dyeing performance on polyester fibers was evaluated, showing moderate to excellent fastness properties. The effects of substituents on color and dyeing properties were discussed, along with the mechanism of dyeing polyester fiber.