Charton’s LDR equation

The rate constants ki were subjected to correlation analyses using various single- and multi-parametric equations the best correlation was obtained using Charton s LDR and LDRS equations. The polar regression coefficients are negative, indicating the formation of a cationic species in the transition state. The reaction is subject to steric hindrance by orf/to-substituents. ... 

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. ... 

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