Залежності розподілу одноатомних фенолів між водою та органічними рідинами

Abstract

Дані по константах розподілу одноатомних фенолів між органічними рідинами та водою можуть бути надійно узагальнені з допомогою лінійних багатопараметричних рівнянь. Процес розподілу визначається, насамперед, основністю екстрагентів, але на нього також впливають їхня полярність та самоасоціація.

Phenols are one of the most widespread and toxic pollutions of natural and industrial waters. Therefore the problem of their analytical determination is of great importance. In case of their very little concentration one employs the preliminary concentration of samples by means of extraction. In that way the problem of selection of optimal extragents becomes important as well as the prognosis of phenols passage from water into organic phase. Widespread is the opinion that the decisive factor which determines the equilibrium constant of phenols distribution between two phases Kp is the interaction of acidic phenols with the basic groups of extragents. However we stated that the interdependence between the logarithm values of phenol acidic dissociation constants in various solvents and their basicity Baccording to Koppel–Palm (change of OH-band in phenol IR-spectrum) is not linear. This disagreement is caused evidently by the influence of some other factors on the distribution process. With the view to obtain a quantitative interdependence between the phenol Kр values and physico-chemical extragent properties we generalized the present Kр data for phenol between water and 29 organic extragents on the basis of free energies linearity principle by means of a sixparameter equation which takes into account a series of extragent characteristics. It turns out that although the Kр value, the very determining factor, is the extragent basicity (the value of pair correlation coefficient r= 0.906), but for receiving of an adequate equation with R= 0.957 it is necessary to take into account the influence of extragents polarity too, which favours the transition of phenol into organic phase, the resembling dependencies were also obtained for 6 other monoatomic phenols and for resorcine. Such approach permits not only the interpretation of the chemismus of phenols distribution between organic and water phases, but sufficiently reliable prevision of Kр values in the case of other non-investigated extragents and the optimization of their selection too.