19322-71-5Relevant articles and documents
Gem-Diol and Hemiacetal Forms in Formylpyridine and Vitamin-B6-Related Compounds: Solid-State NMR and Single-Crystal X-ray Diffraction Studies
Crespi, Ayelén Florencia,Vega, Daniel,Chattah, Ana Karina,Monti, Gustavo Alberto,Buldain, Graciela Yolanda,Lázaro-Martínez, Juan Manuel
, p. 7778 - 7785 (2016/10/13)
The gem-diol moieties of organic compounds are rarely isolated or even studied in the solid state. Here, liquid- and solid-state NMR, together with single-crystal X-ray diffraction studies, were used to show different strategies to favor the gem-diol or carbonyl moieties and to isolate hemiacetal structures in formylpyridine and vitamin-B6-related compounds. The change in position of the carbonyl group in pyridine compounds had a clear and direct effect on the hydration, which was enhanced by trifluoroacetic acid addition. Because of their biochemical importance, vitamin-B6-related compounds were studied with emphasis on the elucidation of the gem-diol, cyclic hemiacetal or carbonyl structures that can be obtained in different experimental conditions. In particular, new racemic mixtures for the cyclic hemiacetal structure from pyridoxal are reported in trifluoroacetate and hydrochloride derivatives.
Acidity Constants of Benzimidazolium Ketone and Pyridinium Aldehyde Hydrates
Owen, Terence C.
, p. 987 - 990 (2007/10/02)
Acidity constants (pKa) of the hydroxyl groups of the quaternary heterocyclonium carbinols 2-hydroxymethyl-1-methylpyridinium and 2-(1-hydroxyethyl)-1,3-dimethylbenzimidazolium ions are 11.5 +/- 0.5.Acidity constants of the corresponding gem diols, the hydrates of 2-formyl-1-methylpyridinium and 2-acetyl-1,3-dimethylbenzimidazolium ions hence are estimated to be 9 +/- 0.5.Accordingly, acidity constants of the hydroxyl groups of pyridine aldehyde salt hydrates are 12-13, not 4-5 as previously reported; and conversely, acidity constants of the pyridinium groups are 4-5, not 12-13.
