- ETUDE PHYSICOCHIMIQUE DE LA DIHYDROXY-3,5 PYRIDINE ET DES ACIDES HYDROXYPYRIDINESULFONIQUES OBTENUS PAR FUSION ALCALINE DU PYRIDINEDISULFONATE-3,5 DE POTASSIUM
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The 3,5-dihydroxypyridine may be obtained with an excellent yield by an two-stepped alkaline fusion of potassium pyridine-3,5 disulphonate.Several hydroxypyridinesulphonics acids may be obtained also following others experimentals conditions.UV spectra off all the ionisation states of those molecules were determined and all the acidity constants, in aqueous solutions, were measured.In a general way, Sulphonates (or sulphonics) substituents strenghten the acidity of both hydroxypyridines and pyridinium cations, and cause hyper- and bathochrome shift of the UV spectra.Contrary to the previous conclusion reported in the litterature, and mainly based on wrong spectrophotometrics data, the 3,5-dihydroxypyridine behave in some cases as zwitterionic form (ca. 100 percent for the monoanion and ca. 50 percent for the neutral molecule in aqueous solution).
- Tersac, Gilles
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p. 265 - 270
(2007/10/02)
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