An electronic spectral study of the coupled effect on the tautomeric equilibria of some α-hydroxy azo compounds

Ahmed, Z. A.; Arta, F.M.; Alla, Mohamed A. Abd; Elmonem, M. E. Abd; Metwally, S. A. M.

doi:10.1016/0584-8539(89)80254-5

Cited by 5 publications

(4 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They can be assigned to the ~r -7r* transition of the naphthalene ring system influenced by the charge transfer originating from the OH-naphthalene ring [14,15]. Absence of this band in the spectra of the compounds I and IV supports this assignment.…”

Section: Spectra In Ethanolic Mediumsupporting

confidence: 53%

Effect of H-bond formation on the electronic spectra of some azo compounds derived from 3-amino-1,2,4-triazole

1998

View full text Add to dashboard Cite

Abstract. The UV-visibie spectra of some azo compounds derived from 3-amino-l,2,4-triazole and various active-methylene or active-hydrogen compounds have been investigated in organic solvents of different polarities. The spectral bands obtained are assigned to the possible electronic transitions. It was found that the azo compounds containing the acetylacetone moiety exist mainly in the hydrazone form, while those containing ethylcyanoacetate, c~ or [3-naphthol substituents exist in an azo ~ hydrazone tautomeric equilibrium in solution. The extra visible band exhibited in the spectra of o-hydroxyazo compound is assigned to an intermolecular electronic transition. The spectral shifts observed in the various organic solvents are discussed on the basis of the solute-solvent interaction through the formation of hydrogen bonds with different species. The variation of the absorbance with pH is employed to determine the acid dissociation constants.

show abstract

Section: Spectra In Ethanolic Mediumsupporting

confidence: 53%

Effect of H-bond formation on the electronic spectra of some azo compounds derived from 3-amino-1,2,4-triazole

1998

View full text Add to dashboard Cite

show abstract

“…Using the spectrophotometric method the isosbestic point wavelength was determined. The spectra for a solution containing a constant concentration of pure iodine (5 1 …”

Section: Methodsmentioning

confidence: 99%

“…The widespread application of pyrazolones as dyes, acid-base, redox, metallochromic indicators, and histological stains has attracted the interest of many investigators (1)(2)(3). The literature survey indicates that limited information is available on the molecular charge-transfer complexes (CT) of pyrazolones with iodine.…”

Section: Introductionmentioning

confidence: 99%

Charge Transfer Complexes of Pyrazolones with Iodine

Ibrahim

1998

Microchemical Journal

View full text Add to dashboard Cite

“…The tautomerism of ortho-hydroxyl aromatic azo compounds is a well-known phenomenon, which has attracted much attention of organic chemistry researchers because of its effects on the stability and properties of the materials (Bershtein and Ginzburg, 1972; Federov, 1988; Lyčka, 2000; Rauf et al , 2015). The influence of solvents and substituents on the structures of the hydroxyl-azo compounds leads researchers to determine the preferred tautomer(s) either in solid or in solution state (Ahmed et al , 1989; Antonov, 2019; Dardeer et al , 2021). It is also an accepted principle that there is a hydrazone ⇌ azo tautomeric equilibrium for hydroxyl-azo dyes in solution state, and this equilibrium can be affected by altering pH value (Lycka, 1993; Noroozi Pesyan et al , 2015; Hristova et al , 2017; Lađarevi et al , 2020; Zhao et al , 2021; Deneva et al , 2019).…”

Section: Introductionmentioning

confidence: 99%

Spectrophotometric studies on some new hydroxyl-azo dyes derived from 6-ethyl-4-hydroxyquinoline-2(1H)-one

Yahyazadeh

Rufchahi²,

Yousefi³

et al. 2022

PRT

View full text Add to dashboard Cite

Purpose This paper aims to synthesize 6-ethyl-4-hydroxyquinolin-2(1H)-one as a new enol-type coupling component in the preparation of some 3-arylazo-4-hydroxyquinolin-2(1H)-one dyes and evaluate the solvent effects on their absorption in ultraviolet-visible spectra. Design/methodology/approach 6-Ethyl-4-hydroxyquinolin-2(1H)-one was synthesized by thermal cyclocondensation reaction of N, N′-bis(4-ethylphenyl) malonamide at 130–140°C in polyphosphoric acid. This compound was then applied in the azo-coupling reaction with some aniline-based diazonium salts, so as to prepare seven new mono-heterocyclic azo dyes. The structures of the compounds were confirmed using mass spectroscopic technique. Fourier transform infra red (FT-IR) and 1H proton nuclear magnetic resonance (1H NMR) and carbon-13 nuclear magnetic resonance (13 C NMR) studies on the structure of the azo compounds revealed that they exist as two E- and Z-isomers of hydrazone tautomer both in solid and solution state. The effects of acid and base on the visible absorption spectra of the dyes were also evaluated and discussed. Findings Ultra violet-visible UV-vis absorption spectra of the dyes didn’t show significant variation by changing of solvents because of intramolecular H-bonding between proposed hydrazone forms and 2- and 4-keto functions in their structures. The spectra of the dyes were not sensitive to the addition of acid but were very sensitive to base. Originality/value The synthesized 3-arylazo-4-hydroxyquinolin-2(1H)-one dyes are new members in the 4-hydroxyquinolin-2(1H)-one azo dyes family, where very few details regarding the synthesis of such dyes are reported before in the literature. They are unique in terms of synthesis and spectral properties.

show abstract

An electronic spectral study of the coupled effect on the tautomeric equilibria of some α-hydroxy azo compounds

Cited by 5 publications

References 5 publications

Effect of H-bond formation on the electronic spectra of some azo compounds derived from 3-amino-1,2,4-triazole

Effect of H-bond formation on the electronic spectra of some azo compounds derived from 3-amino-1,2,4-triazole

Charge Transfer Complexes of Pyrazolones with Iodine

Spectrophotometric studies on some new hydroxyl-azo dyes derived from 6-ethyl-4-hydroxyquinoline-2(1H)-one

Contact Info

Product

Resources

About