Appendix 1-Octanol

In the Appendix C you find the air-water partition constant (Kiaw) of naphthalene and its octanol-water partition coefficient (ATI0W) that you use as surrogate for the fat-water partition coefficient, Kifw). Note that these entities are given as ratios of molar concentrations. Use the fat (octanol) as phase 1 and calculate the fat-air (octanol-air) partition constant, Ki ... 

For estimating the air-olive oil partition coefficient, calculate first the air-octanol partition constant from the air-water (Kisw) and octanol-water (Ki0Vi) partition constants given in Appendix C (Eq. 6-11) ... 

Within a given class of apolar or weakly polar compounds (e.g., alkanes, chlorobenzenes, alkylbenzenes, PCBs), the variation in the air-octanol partition constants (Kiao) is much larger than the variation in the air-water partition constants (Kiaw). For example, the Kim values of the chlorinated benzenes vary between 10 3 5 (chlorobenzene) and 10-7 (hexachlorobenzene, see Hamer and Mackay, 1995), whereas their A, aw values are all within the same order of magnitude (Appendix C). Try to explain these findings. 

Calculate the activity coefficients of (a) n-octane, and (b) aniline in water-saturated (see Table 5.1) u-hexane (%,), toluene (yt), diethylether (yiA), chloroform (y c), n-octanol (y0), and in water from the Kuw values given in Table 7.1. The aqueous solubilities of the two compounds are given in Appendix C. Compare and discuss the results. 

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) ... 

Formulation (7,8) supposes implicitly that the polysoap is unionized in n-octanol (cf to Appendix 1). In order to substantiate this point further, the conductance of the organic phase was also measured as a function of a as shown in Figure 7. The degree of ionization at different a s for hydrogen (aj jj) and for metal (otj ) was determined from the equivalent conductance (see Appendix II). Table HI summarizes these results. 

Quite the most popular of these approaches is multiple regression analysis introduced by Hansch in 1968. In this method, the most favoured variables are (i) partition coefficients (P), from the system octanol/water (Section 3.2) (ii) the sigma (a) and rho (p) values from Hammett s Linear Free Energy Equation (Appendix III) and (iii) Taft s steric factorst E ) which are... 

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