LSER linear solvent energy

LORG (localized orbital-local origin) technique for removing dependence on the coordinate system when computing NMR chemical shifts LSDA (local spin-density approximation) approximation used in more approximate DFT methods for open-shell systems LSER (linear solvent energy relationships) method for computing solvation energy... 

Kamlet-Taft Linear Solvation Energy Relationships. Most recent works on LSERs are based on a powerfiil predictive model, known as the Kamlet-Taft model (257), which has provided a framework for numerous studies into specific molecular thermodynamic properties of solvent—solute systems. This model is based on an equation having three conceptually expHcit terms (258). 

A linear solvation energy relationship (LSER) has been developed to predict the water-supercritical CO2 partition coefficients for a published collection of data. The independent variables in the model are empirically determined descriptors of the solute and solvent molecules. The LSER approach provides an average absolute relative deviation of 22% in the prediction of the water-supercritical CO2 partition coefficients for the six solutes considered. Results suggest that other types of equilibrium processes in supercritical fluids may be modeled using a LSER approach (Lagalante and Bruno, 1998). 

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 ... 

It has been established (Kamlet and Taft 1985) that a large number of solvent effects involving a given solute and a series of solvents can be described by the general linear solvation energy relationship (LSER) ... 

A linear solvation energy relationship (LSER) study of tautomerism in aromatic Schiff bases and related azo compounds indicates that the aminoenone tautomer is always the more polar, and is specifically favoured by proton donor solvents (binding to the second lone pair of the carbonyl). Effects of aromatization and benzo fusion are also discussed.26... 

Many biochemical and toxicological properties of compounds Xt depend on solute-solvent interaction can be rationalized in terms of the linear solvation-energy relationship (LSER) (Kamlet et ah, 1981) ... 

Another important treatment of multiple interacting solvent effects, in principle analogous to Eq. (7-50) but more precisely elaborated and more generally applicable, has been proposed by Kamlet, Abboud, and Taft (KAT) [84a, 224, 226], Theirs and Koppel and Palm s approaches have much in common, i.e. that it is necessary to consider non-specific and specific solute/solvent interactions separately, and that the latter should be subdivided into solvent Lewis-acidity interactions (HBA solute/HBD solvent) and solvent Lewis-basicity interactions (HBD solute/HBA solvent). Using the solvato-chromic solvent parameters a, and n, which have already been introduced in Section 7.4 cf. Table 7-4), the multiparameter equation (7-53) has been proposed for use in so-called linear solvation energy relationships (LSER). 

Eq. (7-53) has been used in the correlation analysis by multiple regression of numerous reaction rates and equilibria, spectroscopic data, and various other solvent-dependent processes. An impressive series of 46 articles entitled Linear Solvation Energy Relationships (LSER) has been published Part 1 [229]... Part 46 [230] see also the summarizing articles [127, 224, 227] and the critical compilation of solvent parameters e.g. n and P) by Abboud and Notario [295]. 

Finally, a multiparameter correlation equation based solely on theoretically determined solvent descriptors, introduced by Famini and Wilson, deserves attention [350], Linear solvation energy relationships (LSERs), such as the KAT equation (7-54) and its successors, can be summarized by the general form shown in Eq. (7-66) ... 

QSAR method based on the philosophy of the -> Linear Solvation Energy Relationships, whose empirically derived molecular descriptors are substituted hy descriptors defined in the framework of - computational chemistry [Famini et ai, 1991 Famini et ai, 1992 Famini and Wilson, 1994a]. The TLSER descriptors were developed with the aim of optimally correlating with LSER descriptors, thereby being as generally applicable to solute/solvent interactions as are the LSER descriptors. 

The above IGC approaches permit determination of ys add base parameters for solid surfaces, however, without the possibility of dedudng them from one single equation. The linear solvation energy relationship (LSER) [75] permits connection of a measured value (e.g., partition coefficient) to the physicochemical parameters of the solute and the solvent (e.g., polymers in the liquid or viscous state) by a five-parameter equation ... 

Infrared Spectral Correlations vntbv. Certain infrared spectral vibration frequencies and parameters derived therefrom show good linearity with the w scale and may also qualify as 7r -type properties. That linear solvation energy relationships (LSERs) apply to ir spectra was first pointed out by Allerhand and Schleyer (34/), who reported that solvent shifts of various types of ir stretching frequencies are proportional to one another. Based on this proportionality, they proposed an empirical LSER for the correlation of solvent sensitive ir vibration frequencies. 

The Comprehensive Table of Solvatochromic Parameters. The /3, tt, and a parameters, determined as described previously for 124 solvents, are assembled in Table 35. Where conflicting values have been published, the results listed here supersede those that have appeared in Parts 1-8 of our Solvatochromic Comparison Method series and Parts 1 -6 of the Linear Solvation Energy Relationships (LSER) series. Findings published in Part 7 and later papers of the LSER series will take precedence over present results. 

Linear solvation energy relationships (LSER) have also been apphed for the evaluation of the retention behavior in RPLC. In LSER, solvent-related properties of solutes, SP e.g., log k, log P w or log aqueous solubility), are described in terms of solvatochromic parameters in the following general form ... 

With this in mind, the Welton group reasoned that the same approach could be taken to the study of the effects of ionic liquids on the rates of reactions. They used the Kamlet-Taft polarity scales to develop Linear Solvation Energy Relationships (LSERs) to describe the effects of solvents on the reaction kinetics of various 8 2 nucleophilic substitution reactions f Schemes 10.1-10.4). 8 2 reactions occur in a concerted step in which the nucleophile replaces the nucleofuge or leaving group as it dissociates from the subsmate. Their reaction profiles have the form of that in Figure 10.1. 

The three scales devised by Kamlet, Abboud and Taft have been used many times to formulate relationships between reaction rate constants and solvent polarity. These are known as linear solvation energy relationships (LSERs). The rate of amide formation for example, the most common single reaction in medicinal chemistry, is inversely proportional to jS for entropic reasons (Figure 3.4). Limonene and its derivative p-cymene were thus justified as excellent options for a renewable amidation solvent, not only in terms of performance but also because they are produced from a renewable feedstock. Other solvents are less suitable according to their solvatochromic polarity parameters (Table 3.3). As hydrocarbons, some aquatic toxicity concerns surround the use of limonene and p-cymene, but ideally these would be minimised with recycling. 

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