Kamlet-Taft multiparametric equation

The study of solute-solvent and solvent-solvent interactions in mixed solvents has been gaining significance in recent years61-64, because of the increasing application of these solvents. Casassas and collaborators67 have used the Kamlet-Taft multiparametric equation for the correlation of dissociation constants of acids in 1, 4-dioxane-water mixtures. They found that when the main solvent is retained the property does not involve significant changes in the cavity volumes and, in those cases, the pK in binary solvents can be described by equation 8 ... 

Multiparametric models of solvent effects are the IMF and the Kamlet-Taft-Abraham equations. 

Equation (10) is only one example of several multiparametric equations that may be used to forecast the effect of variation of solvent on rates of reaction. One such equation that has been applied in organic chemistry is that of Kamlet and Taft (equation 11) ... 

The rate dependence for QFC oxidations of substituted PhCHO in DMSO using p-TsOH as the source of H+ ions has the form k = a + fe[H+]. Kinetics of Michaelis-Menten type and a substantial primary kinetic isotope effect are found. The solvent effects correlate with the Taft and Swain multi-parametric equations. The rates for para- and mera-substituted PhCHO correlate to Charton s triparametric LDR equation, and those for ort/io-substituted PhCHO follow the tetraperametric LDRS relationship. An electron-deflcient reaction centre is proposed for the rate-determining step. " The solvent effects for similarly oxidized maleic, fumaric, crotonic, and cinnamic acids correlate with the Kamlet and Swain multiparametric equations and reflect the cation-solvating power of the solvents. A mechanism involving a three-centre transition state is postulated. ... 

Common features of the tetrakis(pyridine)silver dichromate oxidations of vicinal and non-vicinal diols and their monoethers, aliphatic aldehydes, a-hydroxy acids (glycolic, lactic, malic and few substituted mandelic acids), and aliphatic primary alcohols in DMSO are = a + h[H+], fractional order in the substrates, = 5.91 (ethane diol), 5.80 (MeCHO), 5.78 (mandelic acid), and 5.85 (ethanol). The solvent effects have been analysed using Taft and Swain multiparametric equations for all the substrates except mandelic acid, for which the Kamlet and Swain multiparametric equation is used. The rate constants for aldehydes correlated with Taft s a values with a negative reaction constant. The rate-determining step for oxidation of aldehydes and hydroxy acids is the transfer of H ion. For diol oxidation, the... 

---

See also in sourсe #XX -- [ , ]

---