The structures of l-phenyl-3-methyl-pyrazolone-5 and its benzoyl derivatives have been investigated by means of IR, UV, NMR, and mass spectral spectroscopy. 1-Phenyl 3-methyl-pyrazolone-5 is found to exist as a zwitter ion in the solid state, in the 5-keto form in chloroform and dioxane, and in the 5-hydroxy form in pyridine. The 4-benzoyl derivative of l-phenyl-3-methyl-pyrazolone-5 is shown t...

The potential energy profiles for proton-transfer reactions of 2-hydroxypyridine and its complexes with water were determined by MP2, CASSCF and MR-CI calculations with the 6-31G** basis set. The tautomerization reaction between 2-hydroxypyridine (2HP) and 2-pyridone (2PY) does not take place at room temperature because of a barrier of approximately 35 kcal/mol for the ground-state pathway. The...

In their Review (article number 2001952), Ling Chen, Peng-Yan Fu, Mei Pan and co-workers give a summary introduction of ESIPT (excited state intramolecular proton transfer) materials in the solid including small organic molecules, metal-organic frameworks covalent-organic frameworks. The four-leveled energy cycle based keto-enol emissions these respond to temperature, pressure, solvent, ions, l...

The wobble hypothesis does not discriminate between uracil and thymine. Methylation could favor further stabilization of uracil in the keto form. Thymine is present in keto form only and can pair up but with adenine. Uracil can easily construct the enol form; that is why it forms the U-G pair. In previous E-print I proposed an alternative to the wobble hypothesis [1]. According to my reviewers ...

The study of tautomerics equilibria is vital importance as tautomeric compounds reactivity highly depends on the proportion each tautomer. Herein, equilibrium 3-phenyl-2,4-pentanedione was studied theoretically by b3lyp/6-31+g(d)methods. effect four solvents considered (water, methanol, carbon tetrachloride and Cyclohexane).The takes place through four-membered ring transition state. barrier he...

The title Schiff base compound, C25H19NO2S, crystallizes in a statistically disordered structure comprising keto and enol tautomeric forms. In the enol form, the benzenoid arrangment is promoted by a strong intra-molecular O-H⋯N hydrogen bond and adopts an E conformation about the imine bond. In the keto form there is an intramolecular N-H⋯O hydrogen bond. In the crystal, an extended network of...

TExcited state reaction coordinates and the consequent energy profiles of a new Schiff base, N-salicilydenemethylfurylamine (SMFA), have been investigated with the MP2 and CASSCF method. The potential energy profiles of the ground and the lowest excited singlet state are calculated. The excited state potential energy profile shows a small barrier in the LIIC pathway of dissociation along the O-...

The Acamprosate is a significant drug for alcohol abuse therapy, which may be an effective treatment for tinnitus, too. The Acamprosate has two possible tautomers, Keto and Enol tautomers. Each of the tautomers involves two important conformers. In this work, employing density functional theory (DFT) and handling the solvent effects with the PCM model, the structural parameters, energetic behav...

Recently, a new generation of highly promising inhibitors bearing β-keto-enol functionality has emerged. Reported herein is the first synthesis and use of novel designed drugs based on the β-keto-enol group embedded with heterocyclic moieties such as pyrazole, pyridine, and furan, prepared in a one-step procedure by mixed Claisen condensation. All the newly synthesized compounds were characteriz...

BACKGROUND Several papers described the structure of curcumin and some other derivatives in solid and in solution. In the crystal structure of curcumin, the enol H atom is located symmetrically between both oxygen atoms of the enolone fragment with an O···O distance of 2.455 Å, which is characteristic for symmetrical H-bonds. In the solution, the geometry of the enolone fragment is attributed t...