3-Hydroxy-4-pyridinonate complexes solubilities

We present a selection of solubilities of 3-hydroxy-4-pyridinonate complexes of cations in Table XVII 114,143,144,233-241) and Table XVIII (237), to give some impression of the effects of their variation with the nature of the complex and of the solvent. It is very difficult... 

Despite their importance in many pharmacological uses and potential applications, solubilities of hydroxypyranones, hydroxypyridinones, and their complexes have not been extensively and systematically investigated and established. This situation contrasts sharply with that for partition coefficients, as will become apparent in the following section. The solubility of maltol in water is approximately 0.1moldm , of ethyl maltol 0.13 mol dm, at 298 K. 1,2-Alkyl-3-hydroxy-4-pyridinones show the expected decrease in water-solubility as the sizes of the alkyl groups increase solubilities - in water at 298 K - of l-aryl-2-methyl-3-hydroxy-4-pyridinones decrease from 9 X 10 mol dm for the 1-phenyl compound through 6 x lO- moldm for l-(4 -tolyl) to 6 x 10 mol dm for l-(4 -re-hexyl-phenyl) (37). 

Fig. 9. Normalized solubilities of l,2-dimethyl-3-hydroxy-4-pyridinone, dmppH, of its aluminum(III) and iron(III) complexes AKdmppla and Fe(dmpp)s, and of the 3-hydroxy-4-pyronate complexes Ga(malt)3 and In(etmalt)3 in methanol-water mixtures at 298.2 K (data from Refs. (114) and (234)).

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