Hammett constants, and

TABLE 4. 31P chemical shifts and Hammett constants of N-methyl-iV-arylaminotriphenylphosphonium salts in CHC1344... 

The QSAR models for phenols using resonance constants are apparently more accurate than QSAR models using Hammett constants. The R2 values for QSAR models using resonance constants, oresonancer and Hammett constants, a, were 0.9492 and 0.5473, respectively. The R2 value demonstrates that the QSAR model using resonance constants has a better fit. Figure 5.25 shows the reaction pathway for hydroxyl radical attack on phenols. 

Gross, K.C., Seybold, P.G., Peralta-Inga, Z., Murray, J.S., and Politzer, P., Comparison of quantum chemical parameters and Hammett constants in correlating pKa values of substituted anilines, J. Org. Chem., 66, 6919-6925, 2001. 

CORREL. tON OF C=0. BSORPTION AND Hammett Constants ok 1 -.Scbstituted Acetylf errocenes ... 

Fig. 6. Relationship between Imax and Hammett constants of substituent groups of nickel complex with a correlation coefficient of 0.985.

Figure 3 Correlation between rate of deacylation (to) and Hammett constant (O) of acyl-trypsin. (From Ref. 6.)...

Table 2 Equilibrium ionization constant Ka, pKa values, and Hammett constants cr of selected...

The K s are constants determined by regression analysis. A detailed derivation of the equation can be found in a review by Tute tt). If activity is a function of the steric and electronic nature of the compound s substituents, these effects are assumed to be included in the term K- which can be factored into E and c, the Taft and Hammett constants ot other... 

Fig. 2 The relationship between maximum absorption of the polymeric and monomeric azo dyes and Hammetts constant of substituent on their diazo component...

Table 2). All of the compounds listed in Table 2A and shown in Table 2B have been used in clay sorption studies, and they represent a broad range of aqueous solubilities, polarities, sizes, and Hammett constants. As will be discussed later, sorption is strongly dependent on the number and ring location of the nitro substituents, as well as other functional groups. 

L. Perrin, E. Clot, O. Eisenstein, J. Loch and R. H. Crabtree. Computed ligand electronic parameters from quantum chemistry and their relation to Tolman parameters. Lever parameters, and Hammett constants. Inorg. Chem. 40, 2001, 5806-5811. 

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