Related Experiment Video
Updated: Jun 8, 2026

Syntheses, Crystallization, and Spectroscopic Characterization of 3,5-Lutidine N-Oxide Dehydrate
Published on: April 24, 2018
Tautomerism and microsolvation in 2-hydroxypyridine/2-pyridone
Santiago Mata1, Vanessa Cortijo, W Caminati
1Grupo de Espectroscopía Molecular Edificio Quifima, Area de Química Física, Campus Miguel Delibes, Universidad de Valladolid, 47011 Valladolid, Spain.
Abstract:
The Fourier transform microwave spectra of the hydrated forms of the tautomeric pair 2-pyridinone/2-hydroxypyridine (2PO/2HP) have been investigated in a supersonic expansion. Three hydrated species, 2PO-H₂O, 2HP-H₂O, and 2PO-(H₂O)₂, have been observed in the rotational spectrum. Each molecular complex was confidently identified by the features of the ¹⁴N quadrupole hyperfine structure of the rotational transitions. The presence of water affects the tautomeric equilibrium -N═C(OH)- ↔ -NH-C(═O)-, which is shifted to the enol form for the bare molecules 2PO/2HP but to the keto tautomer for the hydrated forms.
Related Concept Videos
Woodward–Hoffmann Selection Rules and Microscopic Reversibility
Aromatic Hydrocarbon Cations: Structural Overview
Removing one hydrogen from the intervening CH2 group with both...
Five-Membered Heterocyclic Aromatic Compounds: Overview
Thermal Electrocyclic Reactions: Stereochemistry
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Keto–Enol Tautomerism: Mechanism
Basicity of Heterocyclic Aromatic Amines

