Structural studies of tautomeric systems: the importance of association for 2-hydroxypyridine-2-pyridone and 2-mercaptopyridine-2-thiopyridone

Reactions of Hydroxypyridines with 1-Chloro-2,4,6-trinitrobenzene − Product Structure, Kinetics, and Tautomerism

“…In aprotic, poorly polar solvents, the mechanism for the tautomeric equilibrium of 1 involves the dimeric form of 1, which may be the intermediate for both tautomers as in Scheme 10. [8,25,48] The current data show that the rate of the studied reactions is unaffected by the presence of self association. Scheme …”

“…The K T values reported here agree with those reported in the literature. [8,9,45] In particular, the tautomeric forms of 5-chloro-2-hydroxypyridine are present in approximately equal amounts in dioxane, [46] and both tautomers should be detectable. In [D 8 ]THF, however, low-temperature 1 H NMR unfortunately does not provide evidence for the simultaneous presence of both tautomers.…”

“…To obtain more information on the kinetic behaviour of hydroxy pyridines as nucleophiles in S N Ar reactions, and in particular to investigate the nucleophilic power of the different nucleophilic centres of hydroxypyridines, we report data on reactions between 1-chloro-2,4,6-trinitrobenzene (''picryl chloride' ', 9) and the three isomers 2-hydroxypyridine (1), 4-hydroxypyridine (2), and 3-hydroxypyridine (3), as well as 5-chloro-3-hydroxypyridine (7) and 3-hydroxy-6-methylpyridine (8).…”

An ab initio study of the H2O-mediated 1,3-hydrogen rearrangement in the isoelectric series: X, Y = CH2, NH, or O

“…In the present work a systematic study similar to that in ref. 3 1 is made for the 1,3-intramolecular hydrogen rearrangement reaction in water, modeled with a single H 2 0 molecule. Through the remaining text, the direct 1,3-intramolecular hydrogen rearrangement will be referred to as the gas phase case and the 1,3-intramolecular hydrogen rearrangement via a H 2 0 molecule will be referred to as the H20-mediated or supermolecule case.…”

Dynamic Structures of 2-Thiopyrimidone and 2-Thiopyridone in <em>B</em>-Band Absorptions

“…The ground state thiol-thione tautomerization reaction between 2TP and 2MP has been studied extensively in condense phases due to its biological importance. 7,[28][29][30][31][32][33][34][35][36][37][38][39][40] Thiol tautomer, or 2MP (structure II) exists dominantly in the diluted solution of non-polar solvent and in the vapor phase, while thione tautomer, or 2TP (structure I), dominates the equilibrium in the neutral water solution. The experimental investigations from the ultraviolet spectroscopy 29 and free jet microwave (MW) spectroscopy as well as core level photoemission spectroscopy 30 reveal that 2MP is the major protomeric isomer in the vapor.…”