Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Prediction of the activities

Polarity Parameter. Despite their appareat simplicity, these parameters, ( ), show a good correlatioa with plasticizer activity for nonpolymeric plasticizers (10). The parameter is defiaed 2ls (j) = [M A j Po)]/1000 where M = molar mass of plasticizer, = number of carboa atoms ia the plasticizer excluding aromatic and carboxyHc acid carbon atoms, and Pg — number of polar (eg, carbonyl) groups present. The 1000 factor is used to produce values of convenient magnitude. Polarity parameters provide useful predictions of the activity of monomeric plasticizers, but are not able to compare activity of plasticizers from different families. [Pg.124]

Pieratti et ol. (1955) have developed correlations for the prediction of the activity coefficients at infinite dilution for systems containing water, hydrocarbons and some other organic compounds. Their method, and the data needed for predictions, is described by Treybal (1963) and Reid et al. (1987). [Pg.347]

Characterization of THIP at OC1P2Y2S receptors is therefore not predictive of the activity in vivo and may be directly misleading when it comes to addressing the potential for interaction with the benzodiazepines. [Pg.91]

The charges g, of equation (28) may be used as reactivity indices, either intuitively as relative measures of coulombic attraction or electron availability, or through equation (18), bearing in mind that in this case SS" approximates the exact change A, as discussed in Section II. Since the leading term in (28) is unity, predictions of the active positions in derivatives can be made in terms of computed values of the tt, coefficients for the parent hydrocarbons. Moreover, changes with the same sign of Sa necessarily yield the same active positions, which, in practice, provides a theoretical explanation of orientation in benzene derivatives. [Pg.97]

Benson, S. W., and Hougen, G. R., A simple, self-consistent electrostatic model for quantitative prediction of the activation energies of four-center reactions, J. Amer. Chem. Soc. 18,4036 (1965). [Pg.191]

Table II. Prediction of the Activation volume of the Diels-Alder reaction between isoprene and maleic anhydride in supercritical carbon dioxide at 35 C... Table II. Prediction of the Activation volume of the Diels-Alder reaction between isoprene and maleic anhydride in supercritical carbon dioxide at 35 C...
Fan H-J, Hall MB (2001) Recent theoretical predictions of the active site for the observed forms in the catalytic cycle of Ni-Fe hydrogenase. J. Biol. Inorg. Chem. 6 467 173... [Pg.428]

The HLADH-catalyzed reduction of ( )-(97) is of interest since the alcohol product (98) is the thermodynamically less-preferred exo epimer. This emphasizes the fact that the geometry of an initial, kineti-cally controlled, product of an enzyme-catalyzed reduction reflects only the direction of attack of the hydride equivalent that is imposed by the orientation of substrate binding in the ES-complex. In this case, the reduction occurs on the re face of (15 )-(97), in accord with the predictions of the active site... [Pg.200]

From the above it is evident that the proton theory of acids has made possible considerable progress in acidic and basic catalysis and even permitted the quantitative prediction of the activity of new catalysts after a few experiments with other acids or bases. In some cases the prediction can be quite accurate (Kilpatrick and Kilpatrick, 42). [Pg.247]

A similar procedure can be employed for the prediction of the activity coefficient of a solute in any ideal re-component mixed solvent, namely, (1) the re-component ideal mixed solvent can be represented by two (re — l)-component ideal mixed solvents or by one pure solvent and a (re — l)-component ideal mixed solvent, (2) the (re — l)-component ideal mixed solvent can be represented by two (re — 2)-component ideal mixed solvents or by one pure solvent and a (re — 2)-component ideal mixed solvent, and so on. [Pg.182]

The prediction of the activity coefficients of solutes (such as gases and large molecules of biomedical and environmental significance) in saturated solutions of multicomponent mixtures constitutes the main difficulty in calculating the solute solubil-... [Pg.187]

The application of UNIFAC to the solid-liquid equilibrium of sohds, such as naphthalene and anthracene, in nonaqueous mixed solvents provided quite accurate results [11]. Unfortunately, the accuracy of UNIFAC regarding the solubility of solids in aqueous solutions is low [7-9]. Large deviations from the experimental activity coefficients at infinite dilution and the experimental octanol/water partition coefficients have been reported [8,9] when the classical old version of UNIFAC interaction parameters [4] was used. To improve the prediction of the activity coefficients at infinite dilution and of the octanol/water partition coefficients of environmentally significant substances, special ad hoc sets of parameters were introduced [7-9]. The reason is that the UNIFAC parameters were determined mostly using the equihbrium properties of mixtures composed of low molecular weight molecules. Also, the UNIFAC method cannot be applied to the phase equilibrium in systems containing... [Pg.188]

From the total sample set (48 samples), 45 samples were used as calibration samples. The three samples excluded from the calibration set were selected on the basis of a representative variation of their active ingredient concentrations, and finally used as unknown test samples to predict the content of their active ingredients. Partial least squares (PLS) models for each active ingredient were developed with the Unscrambler Software (version 9.6 CAMO Software AS, Oslo, Norway) from the MSC-pretreated median spectra of all pixels of each of the 45 calibration sample images. Based on these calibration models, the predictions of the active ingredient content for each pixel of the imaging data of the three test samples and their evaluation as histograms, contour plots and RGB plots was performed with Matlab v. 7.0.4 software (see below). [Pg.336]

These two relations are the predictions of the activated-complex theory for the frequency factor and the energy of activation. [Pg.51]

The goal of the discussion in the next sections is to show several examples of how fitted densities can be used in order to study large systems where their size prevents the calculation of exact MQSM. In the first section, a study of molecular properties ordering is discussed. Further, calculations of MQSM obtained from fitted densities are applied to the prediction of the activity for a series of metal-substituted enzyme models. Finally, the use of these MQSM as an interpretative tool in chemical reactivity is discussed. [Pg.42]


See other pages where Prediction of the activities is mentioned: [Pg.323]    [Pg.69]    [Pg.120]    [Pg.233]    [Pg.238]    [Pg.373]    [Pg.12]    [Pg.25]    [Pg.108]    [Pg.518]    [Pg.78]    [Pg.670]    [Pg.21]    [Pg.269]    [Pg.104]    [Pg.304]    [Pg.306]    [Pg.16]    [Pg.47]    [Pg.47]    [Pg.16]    [Pg.177]    [Pg.323]    [Pg.217]    [Pg.240]    [Pg.120]    [Pg.666]    [Pg.428]    [Pg.343]    [Pg.47]    [Pg.47]   
See also in sourсe #XX -- [ Pg.324 , Pg.330 , Pg.334 ]




SEARCH



Activation prediction

© 2024 chempedia.info