Structure octanol-water partition coefficients

The flic presented contains 11 data items. The header lines arc property names as used by CACTVS [64, 65], and arc sufficiently self-descriptive. For example, E NHDONORS is the number of hydrogen bond donor.s, E SM1LES" is the SMILES string representing the structure of sulfamidc, and E LOGP is the logP value (octanol/water partition coefficient) for this substance. 

Two approaches to quantify/fQ, i.e., to establish a quantitative relationship between the structural features of a compoimd and its properties, are described in this section quantitative structure-property relationships (QSPR) and linear free energy relationships (LFER) cf. Section 3.4.2.2). The LFER approach is important for historical reasons because it contributed the first attempt to predict the property of a compound from an analysis of its structure. LFERs can be established only for congeneric series of compounds, i.e., sets of compounds that share the same skeleton and only have variations in the substituents attached to this skeleton. As examples of a QSPR approach, currently available methods for the prediction of the octanol/water partition coefficient, log P, and of aqueous solubility, log S, of organic compoimds are described in Section 10.1.4 and Section 10.15, respectively. 

Livingstone, D. J., Ford, M. G., Huuskonen, J. J., Salt, D. W. Simultaneous prediction of aqueous solubility and octanol/water partition coefficient based on descriptors derived from molecular structure. J. Comput.-Aided Mol. Des. 2001, 15, 741-752. 

Broto, P., Moreau, G., Vandycke, C. Molecular structures, perception, autocorrelation descriptor and SAR studies system of atomic contributions for the calculation of the octanol-water partition coefficient. Eur. J. Med. Chem. 1984, 79, 71-78. 

Figure 5.6 The difference between liposome-water and octanol-water partitioning as a function of the octanol-water partition coefficient for a series of unrelated structures [149,385,386,429]. For example, acyclovir partitions into liposomes over 3000 times more strongly than into octanol, and amiodarone partitions into liposomes 100 times more weakly than into octanol. [Avdeef, A., Curr. Topics Med. Chem., 1, 277-351 (2001). Reproduced with permission from Bentham Science Publishers, Ltd.]...

There is a continuing effort to extend the long-established concept of quantitative-structure-activity-relationships (QSARs) to quantitative-structure-property relationships (QSPRs) to compute all relevant environmental physical-chemical properties (such as aqueous solubility, vapor pressure, octanol-water partition coefficient, Henry s law constant, bioconcentration factor (BCF), sorption coefficient and environmental reaction rate constants from molecular structure). 

Polychlorinated biphenyls structure, retention times, response factors, and octanol/water partition coefficients (log Kow)... 

Then there are a number of pesticides, e.g. the phenolic herbicide dinoseb and the fungicide pentachlorophenol, whose speciation varies strongly in the environmental pH-range. For this reason, one has to consider the pwhen estimating their environmental fate. Structures of the compounds discussed in this section are depicted in Table 1, together with a listing of their pand octanol-water partition coefficients, Kow, of the neutral species (unless otherwise indicated). Typical basic pollutants include the industrial chemicals aniline and jV.jV-dimethylaniline. 

The octanol-water partition coefficient, Kow, is the most widely used descriptor of hydrophobicity in quantitative structure activity relationships (QSAR), which are used to describe sorption to organic matter, soil, and sediments [15], bioaccumulation [104], and toxicity [105 107J. Octanol is an amphiphilic bulk solvent with a molar volume of 0.12 dm3 mol when saturated with water. In the octanol-water system, octanol contains 2.3 mol dm 3 of water (one molecule of water per four molecules of octanol) and water is saturated with 4.5 x 10-3 mol dm 3 octanol. Octanol is more suitable than any other solvent system (for) mimicking biological membranes and organic matter properties, because it contains an aliphatic alkyl chain for pure van der Waals interactions plus the alcohol group, which can act as a hydrogen donor and acceptor. 

Octanol/water partition coefficients, Pow, which measure the relative solubilities of solutes in octanol and in water, are widely used as descriptors in quantitative structure-activity relationships (QSAR), for example in pharmacological and toxicological applications.49 Since experimental values of these are not always available, a number of procedures for predicting them have been proposed (see references in Brinck et al.).50... 

A careful comparative pharmacokinetic study of the tripeptoid 6.108 and the tetrapeptide N-phenylacetyl-Leu-Asp-Phe-D-Pro-amide (6.109) in rats has provided insights on absorption and disposition [233]. The two compounds have comparable backbone structures but differ in the presence or absence of peptide bonds. They also have similar octanol/water partition coefficients, although the H-bonding capacity of the tetrapeptide is greater. In an in vitro model, the two compounds had comparable, and low, absorption clearances (6.7 x 10 4 vs. 4.8 x 10 4 ml min-1 cnT1 for the peptoid and the... 

Molecular connectivity indices are desirable as potential explanatory variables because they can be calculated for a nominal cost (fractions of a second by computer) and they describe fundamental relationships about chemical structure. That Is, they describe how non-hydrogen atoms of a molecule are "connected". Here we are most concerned with the statistical properties of molecular connectivity Indices for a large set of chemicals In TSCA and the presentation of the results of multivariate analyses using these Indices as explanatory variables to understand several properties important to environmental chemists. We will focus on two properties for which we have a relatively large data base (1) biodegradation as measured by the percentage of theoretical 5-day biochemical oxygen demand (B0D)( 11), and (2) n-octanol/water partition coefficient or hereafter termed log P (12). 

Hexanone will probably not be bioconcentrated by organisms in water. An octanol/water partition coefficient (K°w) estimates the partitioning of a chemical between octanol and water. Octanol is believed to best imitate the fatty structures in plants and animal tissues. The Kow of 2-hexanone is approximately 20-40, based on its solubility in water (Hassett et al. 1983). These low values suggest that 2-hexanone will not partition to fatty tissues. 

Table 5.15 Elansch structural groups and group contributions for estimating octanol-water partition coefficients...

De Voogt P, Govers H. 1986. Structural and chromatographic predictors of n-octanol/water partition coefficients. Chemosphere 15 1467-1472. 

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