Tautomeric equilibrium and hydroxyl group internal rotation in 4-hydroxypyridine

Sánchez, Raquel; Giuliano, B. M.; Melandri, Sonia; Camináti, Walther

doi:10.1016/j.cplett.2006.04.108

Cited by 15 publications

(24 citation statements)

References 13 publications

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Section: Introductionmentioning

confidence: 98%

“…Rotational studies have been conducted previously on 2HP, 3‐hydroxypyridine (3HP), and 4‐hydroxypyridine (4HP) to assess the effect that the position of the hydroxyl group has on the tautomeric equilibrium. In all cases, the equilibrium was shifted towards the OH s form, but some differences remained for the less abundant species; in 2HP, the C=O form was experimentally observed, whereas the OH a form was found to be predominant for 3HP.…”

Section: Introductionmentioning

confidence: 99%

“…Rotational studies have been conducted previously on 2HP, [12] 3-hydroxypyridine (3HP), [15] and4 -hydroxypyridine (4HP) [16] to assess the effect that the position of the hydroxyl group has on the tautomeric equilibrium. In all cases, the equilibrium was shifted towards the OH s form, but somed ifferences remained for the less abundant species;i n2 HP,t he C=O form was experimentally observed, whereas the OH a form was found to be predominant for 3HP.T he equilibrium was strongly shifted towards the OH form for 4HP (OH s and OH a forms are equivalent by symmetry), and the C=Os pecies was not detected;t his behavior has been explained in terms of dipoledipole interactions.…”

Section: Introductionmentioning

confidence: 99%

“…In all cases, the equilibrium was shifted towards the OH s form, but somed ifferences remained for the less abundant species;i n2 HP,t he C=O form was experimentally observed, whereas the OH a form was found to be predominant for 3HP.T he equilibrium was strongly shifted towards the OH form for 4HP (OH s and OH a forms are equivalent by symmetry), and the C=Os pecies was not detected;t his behavior has been explained in terms of dipoledipole interactions. [16] The tautomeric equilibrium of hydroxypyridines can also be altered by any substitution on the ring by heteroatoms or electrophilic/nucleophilic groups. The nature of such groups is as important as the positiono fs ubstitution.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Chlorination on the Tautomeric Equilibrium of 2‐Hydroxypyridine: Experiment and Theory

Calabrese

Maris

Uriarte

et al. 2016

Chemistry A European J

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What is the most significant result of this study? This work explores the intramolecular proton transfer in the tauto-meric/conformational equilibria of ab iological model system. Previous experiments and theory gave contradictory and nonconclu-sive results due to the subtle balance of inductive and mesomeric effects. In this study,t he role of halogenation at different ring positions and the influence of the solvent on the position of complex conformational and tautomeric equilibria are explored. How did each team contribute to the work? This work stems from ac ollaboration between two research groups, triggered by the Marco Polo exchange program in which Camilla Calabrese participated as aP hD student. The presented results could not be reached without the contributions of each team. The experimental part was performed with the use of two different microwave spectrometers (one at the University of Bolo-gna (Italy) and the other one at the University of the Basque Country (Spain)). The full potential of the spectral range, resolution, and sensitivity had to be exploited for the characterization of the different tautomers and conformers of the chlorine-substituted hydroxy-pyridines in the gas phase, which presents an environment free of intermolecular interactions. The results of extensive quantum chemical calculations both in the gas and in the solvent phases have been the input for the rationalization of the effects of chlori-nation at different positions of the ring. Does the research open other avenues that you would like to investigate? The results were extremely interesting and exciting, and we intend to investigate other examples of molecules that present ac omplex conformational surface, in which substitution of atoms or groups of atoms can have adrastic influence on the stability of the various structural forms. Moreover,w ew ould like to explore the influence of such substitutions on the properties related to intermolecular interactions and reactivity. Invited for the cover of this issue are the groups of EmilioJ.C ocineroa nd Sonia Melandri at the University of PaísV asco and the University of Bologna. The image depicts different possibilities that this tautomeric equilibrium can take according to the differentp ositions of the chlorinea tom, which, in manycases,are difficult to predictapriori. Read the fulltext of the article at

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Chlorination on the Tautomeric Equilibrium of 2‐Hydroxypyridine: Experiment and Theory

Calabrese

Maris

Uriarte

et al. 2016

Chemistry A European J

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“…Furthermore, increasing interest is being shown in the tautomeric equilibrium between 4-hydroxypyridine and 4-pyridone in connection with the physiological action of pyridine and pyrimidine derivatives, e.g. pyrimidine nucleic acid bases [10][11][12][13][14]. On the other hand, cholestery benzoate is the first liquid crystalline compound [15], and in this connection, we have studied the reaction of nucleic acid bases with cholestery p-(ω-bromoalkyloxy)benzoates (1) [16,17].…”

Section: Introductionmentioning

confidence: 99%

Synthesis and liquid crystalline properties of novel pyridine derivatives

Itahara

2008

Journal of Heterocyclic Chem

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Bond Length Alternation and Internal Dynamics in Model Aromatic Substituents of Lignin

et al. 2022

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Broadband microwave spectra were recorded over the 2‐18 GHz frequency range for a series of four model aromatic components of lignin; namely, guaiacol (ortho‐methoxy phenol, G), syringol (2,6‐dimethoxy phenol, S), 4‐methyl guaiacol (MG), and 4‐vinyl guaiacol (VG), under jet‐cooled conditions in the gas phase. Using a combination of 13C isotopic data and electronic structure calculations, distortions of the phenyl ring by the substituents on the ring are identified. In all four molecules, the rC(1)‐C(6) bond between the two substituted C‐atoms lengthens, leading to clear bond alternation that reflects an increase in the phenyl ring resonance structure with double bonds at rC(1)‐C(2), rC(3)‐C(4) and rC(5)‐C(6). Syringol, with its symmetric methoxy substituents, possesses a microwave spectrum with tunneling doublets in the a‐type transitions associated with H‐atom tunneling. These splittings were fit to determine a barrier to hindered rotation of the OH group of 1975 cm−1, a value nearly 50 % greater than that in phenol, due to the presence of the intramolecular OH⋅⋅⋅OCH3 H‐bonds at the two equivalent planar geometries. In 4‐methyl guaiacol, methyl rotor splittings are observed and used to confirm and refine an earlier measurement of the three‐fold barrier V3=67 cm−1. Finally, 4‐vinyl guaiacol shows transitions due to two conformers differing in the relative orientations of the vinyl and OH groups.

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Tautomeric equilibrium and hydroxyl group internal rotation in 4-hydroxypyridine

Cited by 15 publications

References 13 publications

Effects of Chlorination on the Tautomeric Equilibrium of 2‐Hydroxypyridine: Experiment and Theory

Effects of Chlorination on the Tautomeric Equilibrium of 2‐Hydroxypyridine: Experiment and Theory

Synthesis and liquid crystalline properties of novel pyridine derivatives

Bond Length Alternation and Internal Dynamics in Model Aromatic Substituents of Lignin

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