title: Aminequinone-hydroxylquinoneimine tautomeric equilibrium revisited: molecular modeling study of the tautomeric equilibrium and substituent effects in 4-(4-R-phenylamino)naphthalene-1,2-diones.
abstract: Semi-empirical (AM1 and PM3) and DFT (B3LYP/6-31G(d)) calculations were employed to study the tautomeric equilibrium between the aminequinone A and hydroxylquinoneimine B forms of 4-(4-R-phenylamino)naphthalene-1,2-diones. Substituent effects on the tautomeric equilibrium as well as on geometric and electronic parameters were also determined. In the gas phase the hydroxylquinoneimine B form is the most stable, whereas in water the aminequinone A form becomes more stable. The substituents do not modify the relative energies of the two tautomers. These results are in accordance with experimental data reported in the literature.
authors.affiliation: Departamento de Química Inorgânica, Instituto de Química, Universidade Federal Fluminense, Outeiro de São João Batista, s/n, 24020-141, Niterói, RJ, Brazil.
authors.forename: Thaís P
authors.initials: TP
authors.lastname: Fragoso
authors.forename: José Walkimar de Mesquita
authors.initials: JW
authors.lastname: Carneiro
authors.forename: Maria D
authors.initials: MD
authors.lastname: Vargas
mesh_terms: D005740:Gases / Q000737:chemistry; D007536:Isomerism; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D009281:Naphthalenes / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D005740:Gases; D009281:Naphthalenes; D014867:Water; C031721:naphthalene