A theoretical study of tautomerism in dehydroascorbic acid osazone and related tetronic acid derivatives

Shawali, Ahmad S.; Abbas, I. M.; Abdelfattah, Nahed F.; Párkányi, Cyril

doi:10.1016/0008-6215(82)85021-0

Cited by 7 publications

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Convenient synthesis of arylazo derivatives of quinoxaline, 1,4‐benzothiazine, and 1,4‐benzoxazine

Párkányi

Abdelhamid

Shawali³

1984

Journal of Heterocyclic Chem

View full text Add to dashboard Cite

Arylazo derivatives of quinoxaline (1,4‐benzodiazine), 1,4‐benzothiazine, and 1,4‐benzoxazine have been prepared by condensation of hydrazidoyl halides with o‐phenylenediamine, o‐aminothiophenol, and o‐aminophenol, respectively (Table I). This method seems to be more general than the approach using coupling of reactive diazonium salts with, e.g., 277–1,4‐benzothiazine. Both the spectral data and the results of HMO calculations of bonding energies of the azo compounds obtained in this study indicate that they exist predominantly in the hydrazone tautomeric form.

show abstract

Convenient synthesis of arylazo derivatives of quinoxaline, 1,4‐benzothiazine, and 1,4‐benzoxazine

Párkányi

Abdelhamid

Shawali³

1984

Journal of Heterocyclic Chem

View full text Add to dashboard Cite

show abstract

A study of tautomerism in diazonium coupling products of 4‐hydroxycoumarin

Shawali

Harb

Badahdah

1985

Journal of Heterocyclic Chem

View full text Add to dashboard Cite

The spectra (1H nmr, ir and uv) of a series of 3‐arylazo‐4‐hydroxycoumarins 1a‐m indicate that such compounds exist predominantly in the keto hydrazone form 1A both in solid state and in solution. The acid dissociation constants of the series studied were determined spectrophotometrically in 80 vol% ethanol‐water mixture at 27° and ionic strength of 0.1. The results of the correlations of these constants by Hammett and Yukawa‐Tsuno equations exclude the presence of the hydroxyazo form 1B in equilibrium with 1A in agreement with the spectral data. Also, the HMO method has been used to study tautomerism in such compounds. The results are also in full agreement with both the spectral and linear free energy correlations, the hydrazone form 1A being the most stable. It is further shown that both the intermolecular and intramolecular hydrogen bonding favor the hydrazone tautomer.

show abstract

A study of azo-hydrazone tautomerism in 3-phenyl-4-arylazo-5-isozaolones by1H-NMR spectra of15N-labeled compounds and HMO method

1991

View full text Add to dashboard Cite

A theoretical study of tautomerism in dehydroascorbic acid osazone and related tetronic acid derivatives

Cited by 7 publications

References 14 publications

Convenient synthesis of arylazo derivatives of quinoxaline, 1,4‐benzothiazine, and 1,4‐benzoxazine

Convenient synthesis of arylazo derivatives of quinoxaline, 1,4‐benzothiazine, and 1,4‐benzoxazine

A study of tautomerism in diazonium coupling products of 4‐hydroxycoumarin

A study of azo-hydrazone tautomerism in 3-phenyl-4-arylazo-5-isozaolones by1H-NMR spectra of15N-labeled compounds and HMO method

Contact Info

Product

Resources

About