caa a22 4500 477139655 CHVBK 20180405111729.0 cr unu---uuuuu 170330e19971101xx s 000 0 eng 10.1007/BF02768827 doi (NATIONALLICENCE)springer-10.1007/BF02768827 Complete resolution of the ionization equilibria of 5-deoxypyridoxal in water-dioxane mixtures [Elektronische Daten] [Juan Llor, Maria Ros, Salvador Asensio] We have used a potentiometric method to determine the thermodynamic equilibrium constants for the macroscopic ionization processes of 5-deoxypyridoxal (DPL) in water-dioxane mixtures (0-70% weight fraction in dioxane) at temperatures ranging from 10°C to 50°C. These data, together with previously published equilibrium constants for the tautomerism and hydration processes, have allowed us to resolve the complete microconstant system. We have also calculated the microscopic ionization equilibrium constants under all the experimental conditions. The changes of standard thermodynamic function for the macroscopic and microscopic ionization processes were obtained in various water-dioxane mixtures at 25°C. The values of a given microscopic pK with different solvents and temperatures fit very well to an equation which relates this magnitude with the thermodynamic parameters, the solvation of the components of the reaction, and a solvent parameter. We have obtained an interesting linear correlation between the thermodynamic parameters corresponding to all the microscopic ionizations of DPL and the net change of the solvation during the process: enthalpies correlate linearly for all the microscopic ionizations, while entropies do so for the phenols and pyridinium ions separately. Plenum Publishing Corporation, 1997 5-Deoxypyridoxal nationallicence thermodynamic ionization equilibrium constants nationallicence water-dioxane mixtures nationallicence Llor Juan Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18003, Granada, Spain aut Ros Maria Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18003, Granada, Spain aut Asensio Salvador Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18003, Granada, Spain aut Journal of Solution Chemistry Springer US 26/11(1997-11-01), 1021-1036 0095-9782 26:11<1021 1997 26 10953 https://doi.org/10.1007/BF02768827 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02768827 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Llor Juan Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18003, Granada, Spain aut NATIONALLICENCE 700 1- Ros Maria Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18003, Granada, Spain aut NATIONALLICENCE 700 1- Asensio Salvador Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Granada, 18003, Granada, Spain aut NATIONALLICENCE 773 0- Journal of Solution Chemistry Springer US 26/11(1997-11-01), 1021-1036 0095-9782 26:11<1021 1997 26 10953 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer