55135-70-1Relevant academic research and scientific papers
Spectral kinetic characteristics of the photoisomerization products of naphthylmethylideneiminospironaphthopyran induced by photolysis at different wavelengths
Levin,Zaichenko,Shienok,Kol'Tsova,Mardaleishvili,Tatikolov
, (2012)
The spectral kinetic characteristics of intermediates generated by photolysis with light at the wavelengths 337 and 430 or 470 nm of the photobifunctional compound (PBC), 1,3-dihydro-5-(2-hydroxy-1- naphthylmethylideneimino)-1,3,3-trimethylspiro[2H-indole
Factors determining tautomeric equilibria in Schiff bases
Flores-Leonar, Martha,Esturau-Escofet, Nuria,Méndez-Stivalet, José M.,Marín-Becerra, Armando,Amador-Bedolla, Carlos
experimental part, p. 600 - 605 (2012/02/03)
Schiff bases derived from o-hydroxyaldehydes present keto and enol tautomeric forms; the relative equilibrium between these two tautomers depending on the particular aldehyde the Schiff bases is derived from. Thus benzaldehyde produces a stable enol tauto
Substituent and solvent effects on the proton transfer equilibrium in anils and azo derivatives of naphthol. Multinuclear NMR study and theoretical calculations
Alarcón, Sergio H.,Olivieri, Alejandro C.,Sanz, Dionisia,Claramunt, Rosa M.,Elguero, José
, p. 1 - 9 (2007/10/03)
The tautomeric equilibrium due to proton transfer is compared in a series of anils of 2-hydroxynaphthalene-1-carbaldehyde and azo derivatives of 2-naphthol. Although structurally similar, these systems suffer different substituent effects on the solution-state proton transfer properties. The comparative study was performed using 1H, 13C and 15N NMR spectroscopy in a variety of solvents. Hartree-Fock ab initio calculations involving relative stability of tautomers and full geometry optimization for the ground state are in agreement with the experimental observations.
Tautomerism of 2-hydroxynaphthaldehyde Schiff bases
Antonov, Liudmil,Fabian, Walter M.F.,Nedeltcheva, Daniela,Kamounah, Fadhil S.
, p. 1173 - 1179 (2007/10/03)
A UV-Vis spectroscopic study based on the recently developed chemometric approach for quantitative analysis of undefined mixtures is performed on a series of donor and acceptor substituted Schiff bases of 2-hydroxynaphthaldehydes. In CCl4 solution all compounds preferentially exist as the phenol tautomer independent of the nature of the respective substituent. With increasing polarity the tautomeric equilibrium is shifted towards the quinone form. In CHCl3 and, especially, ethanol a clear distinction between the effect of donors (stabilization of the quinone form) and acceptors (stabilization of the phenol tautomer) is evident. Ab initio calculations including solvent effects via the polarized continuum model of solvation as well as the supermolecule approach are used to rationalize the experimental findings.
13C NMR Spectroscopic and AM1 Study of the Intramolecular Proton Transfer in Anils of Salicylaldehyde and 2-Hydroxynaphthalene-1-carbaldehyde
Alarcon, Sergio H.,Olivieri, Alejandro C.,Gonzales-Sierra, Manuel
, p. 1067 - 1070 (2007/10/02)
Tautomeric equilibria in intramolecularly hydrogen bonded Schiff bases is studied on the basis of solution 13C NMR chemical shifts.Variable temperature NMR spectroscopic data and comparison with appropriate models show that while anils of salicaldehyde exist as phenolic tautomers, those of 2-hydroxynaphthalene-1-carbaldehyde exist as equilibrium mixtures containing appreciable amounts of both enol and keto tautomers, the latter being slightly predominant.AM1 results concerning the relative stability of tautomers are in good agreement with the NMR spectroscopic information.
A Broadly Applicable Synthesis of Fluorescent Condensed α-Pyrones
Wolfbeis, Otto S.,Ziegler, Erich,Knierzinger, Andreas,Wipfler, Helmut,Trummer, Iris
, p. 93 - 112 (2007/10/02)
In a two step procedure and in usually good yield an α-pyrone ring can be annelated to (enolized) cyclic β-dicarbonyl compounds like 4-hydroxy-2-pyrones, 4-hydroxycoumarins, 4-hydroxy-2-quinolones and more complex malonylheterocycles, but also to β-naphthole. In a first step the combined action of triethyl orthoformate and arylamines upon the dicarbonyl system affords the anilinomethylene derivatives B in usually high yields.B is reacted with an active methylene nitrile (like alkyl cyano-acetates) and one equivalent of a strong base (like sodium methoxide or potassium hydroxide) in a polar aprotic solvent (like dimethylformamide).Subsequent acidification with dilute aqueous acid gives the corresponding α-pyrone D with yields from 18 to 84percent. The reaction sequence is broadly applicable, which is demonstrated by the synthesis of a series of known (3, 7, 16, 31) and novel (10, 19, 22, 25, 28, 34) heterocyclic systems.Most of them exhibit strong fluorescence in the visible with emission maxima between 450 and 510 nm. - Keywords: Enamines; Fluorescence; α-Pyrone, synthesis
