Water solubility partition coefficient

A number of issues should be considered when assessing the toxicological properties of a new substance and similar substances by read across evaluation. These issues include assessing the similarity of the purity and impurity profiles of the new substance and the similar substances. This is important since there should be no toxicologically meaningful differences in the purities or impurities on a scale that would be likely to influence the overall toxicity. Further, the physicochemical properties of the new substance should be compared with the similar substances. This includes the physical form, molecular mass, water solubility, partition coefficient, and vapor pressure. In addition, the likely toxicokinetics of the substances, including the possibility of different metabolic pathways, should be considered. 

As a rule it has to be stated that halogenated alkylphenols are more active and broader in effectiveness than the alkylphenols. It is therefore in no way astonishing that some of the most important phenol derivatives in practical application are found in this class of phenolics. Among others Klarmann et al. (1933) have carried out systematic examinations of the relationship between chemical structure and antimicrobial activity with regard to halogenated alkylphenols. However, one should not overestimate the value of the data obtained when decisions and selections have to be made for practical application, as other properties of the microbicidal compounds, such as water-solubility, partition coefficient, activity in the presence of interfering factors encountered in practice, and toxicity, are of the same or of even more importance. Although there are available a lot of data and experience, often the optimum compound and formulation must be determined by experiment. 

The ending caine stems from cocaine, the first clinically employed local anaesthetic. Procaine and tetracaine are ester-linked substances, the others are amides. Amide bonded local anaesthetics usually contain two i s in their name, ester-bonded only one. In the structure drawings, the lipophilic portion of the molecule is depicted at the left, the amine at the right. The asterisk marks the chiral centre of the stereoisomeric drugs. Lipid solubility is given as the logarithm of the water octanol partition coefficient, log(P). 

Physicochemical properties Melting point Boiling point Relative density Vapour pressure Surface tension Water solubility Fat solubility Partition coefficient Flash point Flammability Explosivity Autoflammability Oxidizing properties... 

Katritzky, A. R., Wang, Y., Sild, S., Tamm, T., QSPR studies on vapor pressure, aqueous solubility, and the prediction of water-air partition coefficients, J. Chem. Inf. Comput. Sci. 1998, 38, 720-725. 

Baneijee, S., Yalkowsky, S. H., Valvani, S. C. (1980) Water solubility and octanol/water partition coefficients of organics. Limitations of the solubility-partition coefficient correlation. Environ. Sci. Technol. 14, 1227-1229. 

Dotnahska, U., Kozlowska, M.K., and Rogalski, M. Solubilities, partition coefficients, density, and surface tension for imidazoles -t octan-l-ol or -t water or -t n-decane, / Chem. Eng. Data, 47(3) 456-466, 2002. 

Surfactants can act like lipids or emulsifiers in solubilizing flavor materials in surfactant micelles. Headspace analysis techniques were used to follow the release of several common dentifrice flavorants from a solution containing the surfactant sodium lauryl sulfate. Water/micelle partition coefficients were derived to describe the solubilization of the flavorants in tiie surfactant micelle (76). Initially, the flavor is solubilized in the surfactant micelle. As both the micelle and flavor concentration decrease on dilution, flavor compounds, which are highly soluble in the micelle, preferentially increase in the headspace [HGURE11]. 

It should be noted that a connection between hydrophobicity and fat-soluble partition coefficients (n-octanol/water) Pow) has been proposed. The ratio is reported as a logarithm (log Pow) that can be considered a quantitative measure of the hydrophobicity of a compound. Hence, log Pow could be used to predict useful operating HPLC conditions. It would be applicable to hydrophobic compounds, but it may not apply to hydrophilic compounds with a log Pow of less than 2 (23). 

Physicochemical properties are necessary for describing chemical fate, transport, and bio accumulation. The most useful of these are the subcooled liquid vapor pressure (p (, Pa), water solubility ( ig f 1), and the octanol-water (Ko r), octanol-air (Koa) and air-water (Kaw) partition coefficients. The available measured data on these properties for PCN congeners are summarized in Table 3. 

Banerjee, S., S.H. Yalkowsky, and S.C. Valvani. 1980. Water Solubility and Octanol/Water Partition Coefficients of Organics. Limitations of the Solubility-Partition Coefficient Correlation. Environ. Sci. Technol. 14 1427-1429. 

The K values increase rapidly for completely unpolar n-alkanes with increasing water content (Table 9-11). Because of the very low solubility of hydrocarbons and most organic compounds in pure water, the partition coefficients for LDPE/water are either obtained by extrapolating the K values from Table 9-10 to 100 % water, or calculated from two independent measurements of the partition coefficients between... 

Palytoxin is a white, amorphous, hydroscopic solid that has not yet been crystallized. It is insoluble in nonpolar solvents such as chlorophorm, ether, and acetone sparingly soluble in methanol and ethanol and soluble in pyridine, dimethyl sulfoxide, and water. The partition coefficient for the distribution of palytoxin between 1-butanol and water is 0.21 at 25°C based on comparison of the absorbance at 263 nm for the two layers. In aqueous solutions, palytoxin foams on agitation, like a steroidal saponin, probably because of its amphipathic nature. The toxin shows no definite melting point and is resistant to heat but chars at 300°C. It is an optically active compound, having a specific rotation of -i-26° 2° in water. The optical rotatory dispersion curve of palytoxin exhibits a positive Cotton effect with [a]25o being -i-700° and [a]2,j being +600° (Moore and Scheuer 1971 Tan and Lau 2000). 

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