Water Kamlet-Taft parameters

Lu, J., Brown, J.S., Liotta, C.L. and Eckert, C.A., Polarity and hydrogen-bonding of ambient to near-critical water Kamlet-Taft solvent parameters, Chem. Commun., 2001, (7), 665-666. 

Lee mentions also that the acid and base contributions to the surface tension are temperature dependent. For water at 0 °C, the acid and base parts can very well be the same, but at 20 °C flie acid/base ratio is different (and should be around 1.8, when the Kamlet-Taft parameters are given in normalized values). 

The solvent dependency of Katrp was also examined in terms of Kamlet-Taft parameters for 11 solvents and then extrapolated to cover catalyst activity in a total of 28 solvents, including water. The log(KATRp) values measured in this work for Cu Br/l,l,4,7,10,10-hexamethylttiethylenetetramine (HMTETA) + MBriB are plotted against values predicted by the Kamlet-Taft relationship the line representing values predicted by the Kamlet-Taft relationship is shown in Figure 8. Predicted values of Katrp for 16 organic solvents and water are also provided, based on these solvent-independent coefficients and the appropriate solvatochromic parameters. 

A sampling of appHcations of Kamlet-Taft LSERs include the following. (/) The Solvatochromic Parameters for Activity Coefficient Estimation (SPACE) method for infinite dilution activity coefficients where improved predictions over UNIEAC for a database of 1879 critically evaluated experimental data points has been claimed (263). (2) Observation of inverse linear relationship between log 1-octanol—water partition coefficient and Hquid... 

Hydrogen bond donor solvents are simply those containing a hydrogen atom bound to an electronegative atom. These are often referred to as protic solvents, and the class includes water, carboxylic acids, alcohols and amines. For chemical reactions that involve the use of easily hydrolysed or solvolysed compounds, such as AICI3, it is important to avoid protic solvents. Hydrogen bond acceptors are solvents that have a lone pair available for donation, and include acetonitrile, pyridine and acetone. Kamlet-Taft a and ft parameters are solvatochromic measurements of the HBD and HBA properties of solvents, i.e. acidity and basicity, respectively [24], These measurements use the solvatochromic probe molecules V, V-die lliy I -4-n i in tan iline, which acts as a HBA, and 4-nitroaniline, which is a HBA and a HBD (Figure 1.17). 

In this respect, the solvatochromic approach developed by Kamlet, Taft and coworkers38 which defines four parameters n. a, ji and <5 (with the addition of others when the need arose), to evaluate the different solvent effects, was highly successful in describing the solvent effects on the rates of reactions, as well as in NMR chemical shifts, IR, UV and fluorescence spectra, sol vent-water partition coefficients etc.38. In addition to the polarity/polarizability of the solvent, measured by the solvatochromic parameter ir, the aptitude to donate a hydrogen atom to form a hydrogen bond, measured by a, or its tendency to provide a pair of electrons to such a bond, /, and the cavity effect (or Hildebrand solubility parameter), S, are integrated in a multi-parametric equation to rationalize the solvent effects. 

A cmcial component of this treatment is the value of P°w for the distribution of the solute molecules between 1-octanol and water. This could be estimated from group contributions (Hansch and Leo 1979) but could also be related to other properties of the solutes, namely, their solvatochromic parameters according to Kamlet et al. (1984,1988). Their equation was tested for 245 solutes of all kinds with a correlation coefficient of 0.996 and a standard deviation of 0.13. Earlier, Kamlet, Taft and coworkers (Taft et al. 1985, Kamlet et al. 1986) applied the LSER concept directly to the solubility of non-electrolytes in water, independently of the octanol/water distribution. Subsequently, important differences between aliphatic and aromatic solutes were stressed (Kamlet et al. 1987). For liquid aliphatic solutes the expression ... 

However, the quantities already include the interactions of the solutes with water, but properties foreign to such interactions are preferable for predictive purposes. Two such properties have been proposed and tested by Marcus [65] the Kamlet-Taft polarity/polarizability index a (Section 3.3.2.1) and the Hildebrand solubility parameter (Section 3.2.2). These as well as the intrinsic volumes of the solutes, expressed as their McGowan volumes are independent of interactions with water, hence true predictive parameters that are known or calculable from group contributions for a large number of solutes. The predictive expression (for ambient temperatures) is ... 

Table 15.4 shows the acid/base ratios of the van Oss-Good parameters from various sources, as compared to the acid/base ratio predicted from the Kamlet-Taft solvatochromic parameters. The latter parameters are used both in the original form and their normalized values from Lee. We notice that the newest sets of parameters are in better agreement with the water trends predicted from the Kamlet-Taft... 

This behavior of X., or (E = hc/A , with Planck s constant h and velocity of light c) and the dependence on varying substituents or different solvents can be correlated with the Hammet Op parameter and the Kamlet-Taft tt parameter, respectively. With protic solvents and in aqueous solutions, the dependence of the 7T—band maxima on polarity and water content is less clear. The effect of water on the position of the low-energy band in two 4-(donor)-4 -nitroazobenzenes was studied in polyethyleneglycol/water mixtures. Although the polarity of the mixture obviously increased with increasing water content, the values showed a maximum. This could be due to an increased probability of... 

Kamlet, M. J., Doherty, R. M., Carr, P. W., Mackay, D., Abraham, M. H., Taft, R. W. (1988) Linear solvation energy relationships. 44. Parameter estimation rules that allow accurate prediction of octanol/water partition coefficients and other solubility and toxicity properties of polychlorinated biphenyls and polycyclic aromatic hydrocarbons. Environ. Sci. Technol. 22, 503-509. 

Kamlet MJ, Abraham MH, Doherty RM, Taft RW (1984) Solubility properties in polymers and biological media. 4. Correlation of octanol/water partition coefficients with solvatochromic parameters. J Am Chem Soc 106 464-466. 

Since solvatochromic parameters are derived from direct measurements of the energy resulting from intermolecular interaction, they can be used to predict solubility, which is determined by solute-solute, solvent-solvent, and solute-solvent interaction energies. For nonself-associated liquid aliphatic compounds with a weak or nonhydrogen-bond donor (Taft etal., 1985 Kamlet etal., 1986), the solubility in water at 29S was related to molar volunWjf, hydrogen-bond basicity j and polarity/polarizability (jf) by a linear solvation energy relationship (LSER) as in Equation 3.55 ... 

Kamlet, M.J., R.M. Doherty, P.W. Carr, D. Mackay, M.H. Abraham, and R.W. Taft. 1988. Linear Solvation Energy Relationships. 44. Parameter Estimation Rules which Allow Accurate Prediction of Octanol/Water Partition Coefficients and other Solubility and Toxicity Properties of Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons. Environ. Sci. Technol. 22 503-509. 

Kaiser, K.L.E., Dixon, D.G., Hodson, PV. (1984) QSAR studies on chlorophenols, chlorobenzenes and para-substituted phenols. In QSAR in Environmental Toxicology. Kaiser, K. L. E., Ed., pp. 189-206, D. Reidel Publishing Co., Dordrecht, The Netherlands. Kamlet, M.J., Doherty, R.M., Carr, P.W., Mackay, D., Abraham, M.H., Taft, R.W. (1988) Linear solvation energy relationship. 44. Parameter estimation rules that allow accurate prediction of octanol/water partition coefficients and other solubility and toxicity properties of polychlorinated biphenyls and polycyclic aromatic hydrocarbons. Environ. Sci. Technol. 22, 503-509. Kanazawa, J. (1981) Measurement of the bioconcentration factors of pesticides by fresh-water fish and their correlation with physicochemical properties of acute toxicities. Pest. Sci. 12, 417-424. 

Kamlet, M.J., Abraham, M.H., Doherty, R.M. and Taft, R.W. (1984). Solubility Properties in Polymers and Biological Media. 4. Correlations of Octanol/Water Partition Coefficients with Solvatochromic Parameters. J.Am.Chem.Soc., 106,464-466. 

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