Coefficients of a series

Figure 5.4 Comparing liposome-water to octanol-water partition coefficients of a series of uncharged substituted phenols [381-383], [Avdeef, A., Curr. Topics Med. Chem., 1, 277-351 (2001). Reproduced with permission from Bentham Science Publishers, Ltd.]...

Partition coefficients of a series of aliphatic hydrocarbons, including n-hexane, have been determined in human tissues (Perbellini et al. 1985). The following partition coefficients for n-hexane (olive oil/air, blood/air, tissue/air) were determined olive oil, 146 blood, 0.80 liver, 5.2 kidney, 3 brain, 5 fat, 104 muscle, 5 heart, 2.8 and lung, 1. Saline/air partition was not reported separately for n-hexane, but was very low for the range reported for the entire group of compounds (0.1-0.4). 

Wu, Y. C. and W. J. Hamer, (1969). "Osmotic Coefficients and Mean Activity Coefficients of a Series of Uni-Bivalent and Bi-Univalent Electrolytes in Aqueous Solutions at 25°C," National Bureau of Standards Report (NBSIR) 10052, Part XIV, 83 p. 

Furthermore, for most compounds of interest to us, the octanol molecules present as cosolutes in the aqueous phase will have only a minor effect on the other organic compounds activity coefficients. Also, the activity coefficients of a series of apolar, monopolar, and bipolar compounds in wet versus dry octanol shows that, in most cases, Yu values changes by less than a factor of 2 to 3 when water is present in wet octanol (Dallas and Carr, 1992 Sherman et al., 1996 Komp and McLachlan, 1997a). Hence, as a first approximation, for nonpolar solvents, for w-octanol, and possibly for other solvents exhibiting polar groups, we may use Eq. 6-11 as a first approximation to estimate air- dry organic solvent partition constants for organic compounds as illustrated in Fig. 6.2. Conversely, experimental KM data may be used to estimate K,aw or Kitvi, if one or the other of these two constants is known. 

Similarity, affinity, or scaling laws—The equations that state that the head, flow, and power coefficients of a series of pumps are equal. 

In 1995, the diffusion coefficients of a series of polycyclics and their respective dianions as well as corannulene (64) and its tetraanion (64 ) were measured in [DgjTHF solutions [58a]. Upon the formation of the charged species, a large decrease in the diffusion coefficients was observed and, partially, assigned to the increased solvation ofthe charged systems in the [DgjTHF solutions. However, some of the systems showed too large a decrease of their diffusion coefficients upon... 

In many papers in which the reaction rates or adsorption coefficients of a series of substrates were obtained the effect of structure is discussed only qualitatively. Rilzicka and Cerveny (5) found that the rate of hydrogenation of 1-olefins C6-C17 in ethanol under usual conditions on platinum, palladium and rhodium catalysts decreased monotonically with the chain length. Since in this olefinic series the chain length did not affect (68) the relative adsorptivity of olefins, as demonstrated in Table II, the observed phenomenon may be explained only by the effect exerted by the chain length on the rate constants. Since, moreover, the polar effect of substituents in this series is virtually the same, an explanation can be sought in the steric hindrance of the adsorbed double bond by the free end of the olefin molecule. The trans isomers were adsorbed much more weakly than the respective cis... 

In addition to these, the use of several other thermodynamic substituent constants has been investigated (I, 4, 106). For example, Os-trenga used molar attraction constants (107,108), and Turner and Batter-shell have correlated chemical reactivities, vapor pressures, and partition coefficients of a series of isophthalonitriles with their fungicidal properties (109). 

Rase and Kirk 24) have compared the adsorption coefficients of a series of alkylbenzenes calculated for cracking of these hydrocarbons on a silica-alumina catalyst from Eq. (1) with the bond strength of structurally related alkanes and have obtained a linear relation. The correlation coefficient is again high, 0.98. As has been shown in Table I, the corresponding rate constants can be correlated by the Taft equation. However, the plot of log Kj vs a gives a curve. 

A comparison of the permeability coefficients of a series of xenobiotics using Caco-2 cells and an in situ human jejunal perfusion showed that the permeability of compounds with high or complete absorption differed 2- to 4-fold between the in vitro and in situ models, but poorly absorbed compounds differed as much as 30- to 80-fold [18]. Measurement of permeability using Caco-2 cells, therefore, affords only a qualitative comparison. 

The p]< values, solubilities and partition coefficients of a series of On-acylpropranolol prodrugs... were determined. Titrations in a range of aqueous meBianolic solutions were used to estimate the pKg, while titration under non-logarithmic conditions (when excess undissolved base was present in the system) was used to determine solubilities."... 

The principal biological interest of P values is as models for the penetration of drugs through membranes, but to obtain this type of information presents great experimental difficulties. At least we know that the partition coefficients of a series of alcohols between red cell ghosts and water shows a free energy of about —690 cal/mol for the transfer of each methylene group, approximately the same result as between octanol and water (Seeman, Roth and Schneider, 1971). 

John, R. R., Investigation of the Resistance Coefficient of a Series of One-Halfinch Pipe fittings , BS in Engineering Thesis, Princeton, New Jersey, USA (1951). 

Hansch chose logarithms of the partition coefficients of a series of substituted benzenes to define a substituent constant, k, thus... 

The principle of optimal hydrophobicity is illustrated by comparing the octanol water partition coefficients of a series of N-substituted 2-methyl-3-hydroxypyrid-4-ones with their ability to remove iron from hepatocyte cultures (Porter et al. 1988 Porter et al. 1986). Maximal removal of iron from the cells was achieved with derivatives having ATpan values between 0.5 and 1.5 for both the free form and the Fe(III) chelate. Less lipophilic compounds do not enter the cell as readily. Too great a degree of lipo-philicity may caues the chelator to partition into the membrane and not access cytosolic iron pools. Molecular size is also an important feature determining the efficacy of iron chelators. Levin has studied the effects of size and lipophilicity on permeability of the blood-brain barrier, assuming a model of diffusion from bulk aqueous phase to a lipid phase (Levin 1980). Permeability was proportional to P to about 400 daltons. At... 

Alternatively, A/f can be expressed as a function of temperature, and the integration in equation (11) can be carried out accurately, if, as is often the case, the standard heat capacities Q,b have been measured and tabulated (either as such or in the form of coefficients of a series in powers of T) at temperatures over the required range. We then use the relation ... 

One of the classic studies in which the viscosity dependence of kt was investigated originates from the early sixties. North and Reed [62] studied the termination rate coefficients of a series of alkyl methacrylates, in particular MMA [63], These authors used various solvents, all of them exhibiting comparable solvent power for the specific polymers being studied. Only for the smallest methacrylate studied, MMA, an approximate first-order inverse dependence was found between kt and the inherent solution viscosity, /. Several years earlier, Benson and North [40] had reported similar results for MMA and this dependence was later abundantly confirmed by others [66-71, 73, 74, 86]. Also for the monomer styrene this inverse first-order dependence was found [75, 76]. The larger methacrylates also showed an inverse dependence of kt upon solution viscosity, though less strongly than for MMA. 

The macroscopic susceptibilities are the coefficients of a series expansion of the polarization field P with respect to the components of the Maxwell electric field E. Given the Maxwell field... 

Although the diffusion coefficient of a solute in liquid metal is conventionally measured using a capillary method, this method requires highly sophisticated experimental techniques to obtain reliable and reproducible results. On the other hand, diffusion coefficients in electrolytes [6-9] and solid metals [11] are measured by using electrochemical methods which are commonly known to be simple, flexible and sensitive. In a previous study [12], the authors proposed an electrochemical method as the one of techniques to measure a diffusion coefficient in liquid metal and measured the diffusion coefficients of a series of rare earths (La, Pr, Nd, Gd,... 

The Pawlisch model [63] was applied, for example, to calculate the partition coefficient and diffusion coefficients of a series of solvents in PMMA-co-BMA (poly(methyl methacrylate-co-butyl methacrylate)) at infinite dilution [66]. Values of K and Dp that best fitted the experimental data were found, and the model predicted perfectly the system behavior. The Vrentas-Duda free volume theory was found to correctly correlate diffusion data above Tg. 

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