Properties, partitioning

Solubility in water and vapor pressure are both saturation properties, i.e., they are measurements of the maximum capacity that a solvent phase has for dissolved chemical. Vapor pressure P (Pa) can be viewed as a solubility in air, the corresponding concentration C (mol/m3) being P/RT where R is the ideal gas constant (8.314 J/mol.K) and T is absolute temperature (K). Although most chemicals are present in the environment at concentrations well below saturation, these concentrations are useful for estimating air-water partition coefficients as ratios of saturation values. It is usually assumed 

Handbook of Physical-Chemical Properties and Environmental Fate for Organic Chemicals 

When solubility and vapor pressure are both low in magnitude and thus difficult to measure, it is preferable to measure the air-water partition coefficient or Henry s law constant directly. It is noteworthy that atmospheric chemists frequently use Kwa, the ratio of water-to-air concentrations. This may also be referred to as the Henry s law constant. 

The octanol-water partition coefficient KqW provides a direct estimate of hydrophobicity or of partitioning tendency from water to organic media such as lipids, waxes and natural organic matter such as humin or humic acid. It is invaluable as a method of estimating KoC, the organic carbon-water partition coefficient, the usual correlation invoked being that of Karickhoff (1981) 

Seth et al. (1999) have suggested that a better correlation is 

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Biopolymer Extraction. Research interests involving new techniques for separation of biochemicals from fermentation broth and cell culture media have increased as biotechnology has grown. Most separation methods are limited to small-scale appHcations but recendy solvent extraction has been studied as a potential technique for continuous and large-scale production and the use of two-phase aqueous systems has received increasing attention (259). A range of enzymes have favorable partition properties in a system based on a PGE—dextran—salt solution (97) ... 

Other properties that are influenced by H bonding are solubility and miscibility, heats of mixing, phase-partitioning properties, the... 

Bodor, N., Buchwald, P. Molecular size based approach to estimate partition properties for organic solutes. J. Phys. Chem. E 1997, 101, 3404-3412. 

Polyalphaolefin Hydraulic Fluids. The transport and partitioning properties of the polyalphaolefin hydraulic fluids will be similar to the mineral oil fluids since they contain similar aliphatic hydrocarbon... 

In Section 4.8 the topic of charged-species absorption ( fact or fiction ) was first considered. The partitioning properties of some lipophilic charged molecules in the... 

An advantage of the fugacity capacity approach is that for N compartments N values of Z are defined while there may be N(N-l)/2 partition coefficients. Using Z values the partitioning properties between two phases are attributed independently to each phase. It is possible to assign (accidentally) three inconsistent partition coefficients between air, soil and water but the three Z values are inherently consistent. 

Perhaps in light of the mechanism-based side effects, the therapeutic potential of SCD inhibitors has not been fully evaluated. The possibility exists that at least some of the chronic effects of SCD inhibition might be prevented by coadministration of fish oils or potentially a Toll4 antagonist [20]. However, coformulation of an SCD inhibitor with fish oil has not been reported. Another possibility is that SCD inhibitors with appropriate PK and tissue partitioning properties may limit mechanism-based side effects. 

All partitioning properties change with temperature. The partition coefficients, vapor pressure, KAW and KqA, are more sensitive to temperature variation because of the large enthalpy change associated with transfer to the vapor phase. The simplest general expression theoretically based temperature dependence correlation is derived from the integrated Clausius-Clapeyron equation, or van t Hoff form expressing the effect of temperature on an equilibrium constant Kp,... 

Because of the requirements of regulations for certain chemicals such as pesticides, extensive data usually exist on partitioning properties and reactivity or half-lives of active ingredients. In some cases these data have been peer-reviewed and published in the scientific literature, but often they are not generally available. A reader with interest in a specific pesticide can often obtain additional data from manufacturers or from registration literature, including accounts of chemical fate under field application conditions. Frequently these data are used as input to pesticide fate models, and the results of these modeling exercises may be available or published in the scientific literature. 

Clark, E.C.W., Glew, D.N. (1966) Evaluation of thermodynamic functions from equilibrium constants. Trans. Farad. Soc. 62, 539-547. Cole, J.G., Mackay, D. (2000) Correlating environmental partitioning properties of organic compounds The three solubility approach . Environ. Toxicol. Chem. 19, 265-270. 

Dickhut, R.M., Miller, K.E., Andren, A.W. (1994) Evaluation of total molecular surface area for predicting air water partitioning properties of hydrophobic aromatic chemicals. Chemosphere 29, 283-297. 

Basak, S. C., Mills, D. Prediction of partitioning properties for environmental pollutants using mathematical structural descriptors. ARKIVOC 2005, 2005(b), 60-76. 

Solubility, solvation, and partition properties of ligands and complexes are of central importance to many applications. Most... 

Environmental Fate. Experimental data are available regarding the transport and partitioning properties of chloroform in surface waters (Bean et al. 1985 Clark et al. 1982 Class and Ballschmidter 1986 Dilling 1977 Ferrario et al. 1985 Piwoni et al. 1986 Sawhney 1989). Chloroform partitions mainly into the atmosphere and into groundwater. Empirical measurements or model predictions on half-disappearance times in such media as soil could not be identified in the literature. Chloroform can be transported long distances in air. Data are available regarding the degradation of chloroform in the... 

Kralj, F. and Sincic, D. Mutual solubilities of phenol, salicyaldehyde, phenol-salicyaldehyde mixture, and water with and without the presence of sodium chloride and sodium chloride plus sodium sulfate, J. Chem. Eng. Data, 25 (4) 335-338,1980. Kramer, C.R. and Henze, U. Partitioning properties of benzene derivatives. 1. Temperature dependence of the partitioning of monosubstituted benzenes and nitrobenzenes in the n-octanol/water system, Z. Phys. Chem., 271(3) 503-513,1990. Krasnoshchekova, R.Ya. and Gubergrits, M. Solubility of paraffin hydrocarbons in fresh and salt water, Neftekhlmlya, 13(6) 885-888, 1973. 

As previously noted, the partition properties of the bisindole alkaloids tend to be lipophilic. The octanol-water partition coefficients of several bisindole derivatives have been measured and compared to various bio-... 

The prediction of the partition properties of peptide molecules is difficult, owing to their conformational flexibility, and the possible presence of multiple intramolecular hydrogen bonds and ionizable groups. Richards and coworkers (40-42) were the first to consider explicitly the effects of the population of accessible conformational minima in both phases. These types of calculation are, however, computationally intensive. The introduction of the solvent-accessible surface area in the prediction of log Poct for steric isomers (43,44) also constitutes a promising approach. 

Arey, J.S., Nelson, R.K., Xu, L., Reddy, C.M. (2005) Using comprehensive two-dimensional gas chromatography retention indices to estimate environmental partitioning properties for a compete set of diesel fuel hydrocarbons. Anal. Chem. 77 7172-7182. 

Thus, structure-activity relationships developed to estimate levels in biological media based on the partitioning properties of a chemical may not provide accurate information for isophorone. Furthermore, only one bioaccumulation study was available. In this study, which indicated a low potential for bioaccumulation, fish were exposed to isophorone in water rather than in food. From these data, it appears that food chain bioaccumulation may be occurring, and a clearer understanding of the potential for this would aid in determining how levels in the environment affect the food chain and potentially impact on human exposure levels. 

Solvatochromic Approach Solvatochromic relationships are multivariate correlations between a property, usually solubility or partitioning property (see Sections 11.4 and 13.3), and solvatochromic parameters, parameters that account for the solutes interaction with the solvent. In the case of vapor pressure, the solvatochromic parameters only have to account for intermolecular interaction such as selfassociation between the solute (i.e., pure compound) molecules themselves. The following model has been reported for liquid and solid compounds, including hydrocarbons, halogenated hydrocarbons, alkanols, dialkyl ethers, and compounds such as dimethyl formamide, dimethylacetamide, pyridine, and dimethyl sulfoxide... 

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