Octanol/water partition constant

Danielsson, L.-G. Zhang, Y.-H., Methods for determining n-octanol-water partition constants, Trends Anal. Chem. 15, 188-196 (1996). 

Dithiocarbamates and xanthates form particularly stable, neutral complexes with Cu(II), Cd(II) (and also Ni, Hg, Pb), which are membrane permeable and increase the apparent bioaccumulation of these metals [13]. In the series of sulfoxine, oxine, and chloroxine, the hydrophobicity of the neutral and the charged form, as well as of the Cu complex, increases. While the sulfoxine is not hydrophobic and does not modulate copper toxicity [220], the Cu-oxine complex is hydrophobic with an octanol-water partition constant, log Kok, of 1.7 [221] or 2.6 [222]. Chloroxine can be assumed to be even more hydrophobic, but so far its influence on uptake and toxicity has not been investigated. Uptake of Cu2+ into unilamellar liposomes was increased in the presence of 8-hydroxy-chinoline, and decreased again after adding HA [223],... 

Fig. 17.3. Calculation of the oxazolidine offsets from a specific example. From the product (P) property, each of the reagent (Rj) property is subtracted. Four properties are considered the number of hydrogen bond acceptors (HBA), the number of hydrogen bond donors (HBD), the number of non-hydrogen atoms (NHA), and the logarithm of the octanol/water partition constant (log P).

Octanol-water partition constant and aqueous solubility of the pure liquid compound l°g - iow = -a- logCf + b 7... 

Natural organic carbon-water partition coefficient and octanol-water partition constant logKioc = alogKiow + b 9... 

The special interaction terms are necessary to describe intramolecular interactions between different parts of the molecule that cannot be accounted for when considering the transfer of the isolated parts. Obviously, this type of approach has a big advantage in that it allows one to estimate a partition constant based solely on the compound s structure. Good results can be anticipated particularly in those cases where the partition constant of a structurally closely related compound is known, and thus only the contributions of the parts that are different between the two compounds have to be added and/or subtracted, respectively. The most advanced and most widely used method that is based on this concept is the structural group contribution method for estimating octanol-water partition constants. We will discuss this method in Chapter 7. 

One-Parameter LFERs for Estimation of Octanol-Water Partition Constants Polyparameter LFERs for Estimation of the Octanol-Water Partition Constant... 

Illustrative Example 7.2 Estimating Octanol-Water Partition Constants from Structure Using the Atom/Fragment Contribution Method Illustrative Example 7.3 Estimating Octanol-Water Partition Constants Based on Experimental KI0W s of Structurally Related Compounds... 

We start, however, with some general thermodynamic considerations (Section 7.2). Then, using our insights gained in Chapter 6, we compare solvent-water partition constants of a series of model compounds for different organic solvents of different polarity (Section 7.3). Finally, because n-octanol is such a widely used organic solvent in environmental chemistry, we will discuss the octanol-water partition constant in somewhat more detail (Section 7.4). 

Table 7.3 LFERs Between Octanol-Water Partition Constants and Aqueous Activity Coefficients or Liquid Aqueous Solubilities at 25°C for Various Sets of Compounds Slopes and Intercepts of Eqs. 7-10 and 7-11... 

One-parameter LFERs for Estimation of Octanol-Water Partition Constants... 

Polyparameter LFERs for Estimation of the Octanol-Water Partition Constant... 

Estimating Octanol-Water Partition Constants from Structure Using the Atom/Fragment Contribution Method... 

Illustrative Example 7.3 Estimating Octanol-Water Partition Constants Based on Experimental A,-ow s... 

Table 9.2 LFERs Relating Particulate Organic Matter-Water Partition Coefficients and Octanol-Water Partition Constants at 20 to 25°C for Some Sets of Neutral Organic Compounds Slopes and Intercepts of Eq. 9-25a... 

Figure 10.13 Plot of log 1/LC,S0 for guppies (small tropical fish, Poecilia reticulata) versus (a) log octanol-water partition constant (log A ,ow), and (b) log L-a-dimyristoylphosphatidylcholine liposome-water coefficient (log A)]ipsw) for a series of neutral apolar and weakly polar (o) and polar (t) compounds. Data from Gobas et al. (1988), Vaes et al. (1998), and Gunatilleka and Poole (1999).

When is the n-octanol-water partition constant an acceptable parameter for the quantification of nonspecific membrane toxicity In what situations does it fail ... 

Octanol-water partition constant ow (-) 6.0 xlO5 2.0 xlO7... 

Estimate Koc from the octanol-water partition constant, Kow, using the linear free energy relationship (Eq. 9-26f), with log Kov/ = 2.88 (Appendix C) ... 

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