Protonation Constants of Uridine 5′-Monophosphate in Different Aqueous Solutions of Methanol

Soleimani, Farahnaz; Gharib, Farrokh

doi:10.1007/s10953-014-0161-8

Cited by 1 publication

(1 citation statement)

References 32 publications

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“…The multiparametric equation, Eq. (8), has been proposed using the solvatochromic solvent parameters (α, β and π * ) which have been introduced in previous literatures [28][29][30][31][32]. logK = Aₒ + aα + bβ + pπ* (8) where Aₒ is the regression value and π* is the index of the solvent dipolarity/polarizability, which shows the ability of a solvent to stabilize a charge or a dipole by its own dielectric effects.…”

Section: Solvent Effectmentioning

confidence: 99%

Solvent Effects on Protonation Constants of Betanin in Different Aqueous Solutions of Methanol at T = 25 ºC

et al. 2019

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Abstract. The protonation constants of the betanin (pKa1, pKa2, and pKa3) were determined in mixed solvent of water and methanol containing 0, 10, 20, 30, 40, 50, 60, 70, and 80 % (v/v) methanol, using a combination of the spectrophotometric and potentiometric methods at T = 25 ºC and constant ionic strength (0.1 mol.dm-3 NaClO4). The obtained protonation constants were analyzed using Kamlet, Abboud, and Taft parameters. KAT parameters are α (hydrogen-bond donor acidity), β (hydrogen-bond acceptor basicity), and π* (dipolarity/polarizability). In this study, a good linear relationship was obtained between protonation constants (on the logarithmic scale) and dielectric constant (ɛ) of the water-methanol mixed solvents. It was found that the dual-parameter correlation between log10K,s and π*, β give us the best result in various volume fractions of methanol for water-methanol mixed solvent. Finally, the results are discussed in terms of the effect of the solvent on the protonation constants. Resumen. Las constantes de protonación de la betanina (pKa1, pKa2 y pKa3) se determinaron en un disolvente mixto de agua y metanol que contenía metanol al 0, 10, 20, 30, 40, 50, 60, 70 y 80% (v / v), utilizando una combinación de los métodos espectrofotométricos y potenciométricos a T = 25 ºC y fuerza iónica constante (0,1 mol.dm-3 NaClO4). Las constantes de protonación obtenidas se analizaron utilizando los parámetros de Kamlet, Abboud y Taft. Los parámetros KAT son α (acidez del donante de enlaces de hidrógeno), β (basicidad del aceptor de enlaces de hidrógeno) y π* (dipolaridad / polarizabilidad). En este estudio, se obtuvo una buena relación lineal entre las constantes de protonación (en la escala logarítmica) y la constante dieléctrica (ɛ) de los disolventes mixtos agua-metanol. Se encontró que la correlación de doble parámetro entre log10K, s y π*, β nos da el mejor resultado en varias fracciones de volumen de metanol para el disolvente mixto agua-metanol. Finalmente, los resultados se discuten en términos del efecto del solvente en las constantes de protonación.

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