| Titre : |
On the NH and CH acidities of toluidine isomers : theoretical description and practical consequences for the synthesis of certain aniline dyes |
| Type de document : |
texte imprimé |
| Auteurs : |
Vladimir Lukes, Auteur ; Horst Hartmann, Auteur |
| Année de publication : |
2021 |
| Article en page(s) : |
p. 389-398 |
| Note générale : |
Bibliogr. |
| Langues : |
Anglais (eng) |
| Catégories : |
Acides et bases, Théories des
Aniline
Colorants
Oxydation
Toluidine
|
| Index. décimale : |
667.2 Colorants et pigments |
| Résumé : |
For the toluidine isomers, amino group acidity represents a characteristic feature of these compounds in their electric neutral state. As demonstrated by theoretical calculations based on the quantum chemistry composite G4 method and density functional theory, the CH acidity of the methyl group is hidden under NH acidity. The transformation of toluidines into their mono- and bi-oxidised states significantly increases the acidity of the methyl group. This study indicates that the presence or absence of these deprotonated species in reaction mixtures will determine the CN or CC coupling toluidine products. In agreement with published synthetic approaches for aniline dyes, such as mauveine and fuchsine, the results obtained explain the alternative reaction pathways occurring during the oxidation of toluidine isomers. |
| Note de contenu : |
- COMUTATIONAL METHODOLOGY
- RESULTS AND DISCUSSION : Thermodynamics of the toluidine acid-base reaction - Theoretical pKa values of toluidine oxidation states - Oxidation states and the reactivity of toluidine
- Table 1 : Reaction G4 Gibbs free energies for selected acid-basic steps (energies in kJ mol-1)
- Table 2 : The predicted pKa values from the isodesmic reaction and G4 (integral equation formalism-polarisable continuum model) calculations |
| DOI : |
https://doi.org/10.1111/cote.12536 |
| En ligne : |
https://onlinelibrary.wiley.com/doi/epdf/10.1111/cote.12536 |
| Format de la ressource électronique : |
Pdf |
| Permalink : |
https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36103 |
in COLORATION TECHNOLOGY > Vol. 137, N° 4 (12/07/2021) . - p. 389-398
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