Synthesis of some novel hetarylazo disperse dyes derived from 4-hydroxy-2H-1-benzopyran-2-one (4-hydroxycoumarin) as coupling component and investigation of their absorption spectra

A study on tautomeric investigation of new hetarylazo-6-aminouracil

“…Generally, most of the substituted dyes have higher absorption maxima than their unsubstituted analogs. In the present study, spectral data for the various substituted hetarylazouracil dyes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) show that there is a general tendency for the visible absorption band to move bathochromically in accordance with the electron donor-acceptor groups in the diazo and coupling component. These involve a migration of electron density from the donor group toward the azo group.…”

“…The absorption spectra of hetaryl-azouracil dyes (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) were measured in various solvents at a concentration approximately 10 -6 -10 -8 M, run at different concentrations because of solubility problems ( Table 1). All the dyes have low solubility in chloroform which is the least polar solvent I used, and the absorption spectrum was only recorded in chloroform for dye 12.…”

“…These results led to commercial products to replace the conventional azobenzene disperse dyes. [13][14][15][16][17][18] Nitro-substituted aminothiophenes and aminothiazoles are primarily of importance as diazo components. [19][20][21][22][23][24] Recently, Towns has summarized the developments in azo disperse dyes derived from heterocyclic diazo components.…”

“…A change of λ max was investigated when 0.1 mL piperidine was added to 1 mL of dye solutions in DMSO and DMF, or when 0.1 mL base (potassium hydroxide, 0.1 M) or 0.1 ml acid (hydrochloric acid, 0. (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) Diazotization of various heterocyclic amines was effected with nitrosylsulfuric acid. A typical procedure is described below for 2-aminothiazole; all other dyes were prepared in a similar manner.…”

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

“…Another interesting feature of this class lies on its tautomeric behavior which has been studied by several investigators for many years. They were originally regarded as azo-structure (A) [7,8], but others workers [9][10][11] tended to the view that they were keto-hydrazone structure (D). Recently, two groups of workers [12,13] proposed that compounds exist as a mixture of tautomeric forms(A) and (D) (Fig.…”