Kinetic investigation of the oxidation of substituted arylazonaphthol dyes by hydrogen peroxide in alkaline solution

Kinetic study of the manganese‐based catalytic hydrogen peroxide oxidation of a persistent azo‐dye

“…This result is certainly in agreement with the literature. Gilbert et al (2003) 17 and Oakes et al (1998) 29 have also reported slow reaction kinetics for the oxidation of dyes using uncatalysed hydrogen peroxide. The slight enhancement of the dye oxidation observed when the pH increased was possibly due to the ionisation of H 2 O 2 .…”

Interaction of surfactants and aminoindophenol dye

“…The pKa can be determined by UV-vis spectra [13,14]. At certain pH and wavelength, the spectra of the undissociated dye (HD) and dissociated dye (D − ) are additive as Eq.…”

Azocoupling products. V. Electronic spectroscopy study of two azocoupling products of 1-(4-hydroxy-6-methyl-pyrimidin-2-yl)-3-methyl-pyrazolin-5-one

“…1e3, 5e11) can be explained most reasonably by the assumption of an equilibrium between the assigned hydrazone tautomer 7c or 8c and at least an other species (cf. [1e 19,21,22]). The proposed other species are transformed by addition of acid or water into the hydrazone tautomer and the hydrazone tautomer is converted by addition of alkali in the proposed other species at least partially (Figs.…”

“…As with other azoanions (cf. [1,12,16,18,19,21]) the electron-releasing substituent (CH 3 ) in the para position of the benzene ring with respect to the azo group of these dyes determines an absorption maximum at lower wavelength (circa 390 nm) than that caused by the electron-withdrawing substituent (NO 2 ) (circa 470 nm).…”