Pyridone may refer to several organic compounds with the formula :
*
2-Pyridone
*3-hydroxypyridine
*
4-Pyridone
4-Pyridone is an organic compound with the formula . It is a colorless solid.
Preparation
4-Pyridone, and its derivatives, are prepared from 4-pyrone and amines in protic solvents.
:
Tautomerism
4-Pyridone exists a keto-enol tautomerism with ...
These can adopt three
tautomers, a oxo form, a
zwitterion
In chemistry, a zwitterion ( ; ), also called an inner salt or dipolar ion, is a molecule that contains an equal number of positively and negatively charged functional groups.
:
(1,2- dipolar compounds, such as ylides, are sometimes excluded from ...
form, and a enol form. Whereas 2-pyridone (α) and 4-pyridone (γ) predominantly adopt the oxo form, the 3-pyridone (β) cannot, and instead adopts an equilibrium of the
zwitterion
In chemistry, a zwitterion ( ; ), also called an inner salt or dipolar ion, is a molecule that contains an equal number of positively and negatively charged functional groups.
:
(1,2- dipolar compounds, such as ylides, are sometimes excluded from ...
form, pyridin-1-ium-3-olate, and the enol form, 3-hydroxypyridine (the canonical form). The 3-pyridone is not
mesoionic
In chemistry, mesoionic compounds are one in which a heterocyclic structure is dipolar and where both the negative and the positive charges are delocalized. A completely uncharged structure cannot be written and mesoionic compounds cannot be repr ...
. This property of 3-hydroxypyridine is leveraged in biology in
pyridoxal phosphate
Pyridoxal phosphate (PLP, pyridoxal 5'-phosphate, P5P), the active form of vitamin B6, is a coenzyme in a variety of enzymatic reactions. The International Union of Biochemistry and Molecular Biology has catalogued more than 140 PLP-dependen ...
: this common cofactor that catalyses a variety of reactions thanks to a stable cationic form.
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