Theory of Salting-Out

Two aspects of the theory of salting out are considered below. First, the effects of the primary solvation sheath have to be taken into account how the requisition of water by the ions causes the nonelectrolyte s solubihty to decrease. Second, the effects of secondary solvation (interactions outside the solvation sheath) are calculated. The... 

It is recognized (26, 27) that electrostatic theories of salting out of the kind developed by Debye and Kirkwood (23) do not account for the large differences between the effects of different salts, such as is evident in the preference of phosphate for amide group binding. Whether this preference and relative prevention of the denaturation reaction implicates an interaction with a changing structure of liquid water has yet to be determined (26, 28). 

Prediction of salting out effect based on scaled particle theory... 

In the last one and a half to two decades, the KB theory of solutions was successfully used to predict the solubility in numerous systems. Indeed, it is quite impressive that one method was successful for such different systems as those examined in this chapter the solubility of gases and drugs and hydrophobic organic pollutants in binary and multicomponent mixed solvents and the solubility of protein. In addition, this method was successfully applied to the solubility of solids in supercritical fluids, to the solubility of mixed gases in individual solvents, to the explanation of salting-out phenomena (Ruckenstein and Shulgin 2009). In some cases (multicomponent mixtures) the KB theory of solutions constitutes the most powerful theoretical method for investigating the thermodynamic properties. 

In order to complete the reaction, heating at 50°C is carried out for 3 hours. After cooling, one liter of benzene is added and the reaction mixture is stirred, then washed salt-free with water. The benzene solution is dried over anhydrous sodium sulfate, filtered and concentrated by evaporation giving 167 g crude 1-(o-chlorophenylbisphenylmethyl)-imidazole. By recrystallization from acetone, 115 g (= 71% of the theory) of pure 1-(o-chlorophenyl-bisphenylmethyD-imidazole of MP 154° to 156°C are obtained. 

Thus, a suitable refinement of the Debye-Huckel theory must provide a theoretical interpretation of the term CL Originally this term was qualitatively interpreted as a salting-out effect during solvation the ions... 

Recently, Melander and Horvath (7, 10) have proposed a single theory to account for the effects of neutral salts on the electrostatic and the hydrophobic interactions in the salting out and the chromatography of proteins. In simplified terms, the theory accounts for the solubility of proteins in terras of two contributions, electrostatic and hydrophobic in nature. 

The combination of the hydrophobic salting out and the electrostatic salting in terms explains very nicely the Class I type behavior. The data for carboxyhemoglobin and fibrinogen are well fitted by the theory (Figure 10). Also the order of decreasing molal surface tension increment generally follows the lyotropic order (7). 

Fig. 4. Simplified version of Digby s semiconductor theory of biomineralization. In the arthropod (top) ions are continually diffusing out of the animal across the cuticle at different rates setting up a potential with the outer surface positive. This causes a flow of electrons leaving the inner surface rich in proteins and the outer surface with hydroxyl ions. The alkaline outer surface favors CaC03 formation. In molluscs (bottom) muscular movements cause salt flow through the periostracum followed by an alkaline reaction on the inside inducing CaC03 deposition. (After Simkiss445 )...

Isothermal vapor-liquid equilibrium data at 75°, 50° and 25° C for the system of 2-propanol-water-lithium perchlorate were obtained by using a modified Othmer still. In the 2-propanol-rich region 2-propanol was salted out from the aqueous solution by addition of lithium perchlorate, but in the water-rich region 2-propanol was salted in. It is suggested from the experimental data that the simple electrostatic theory cannot account for the salt effect parameter of this system. 

The 195-260° fractions of the distillates are treated with potassium carbonate to salt out the allyl alcohol and to neutralize the little formic acid present. This allyl alcohol is then distilled and the fraction boiling up to about 103° is collected, or if a column is used, up to 98°. In this way, 845 g. of an allyl alcohol are obtained, which by a bromine titration shows a purity of about 68-70 per cent. This is equivalent to 5 70 to 590 g. of pure allyl alcohol (45-47 per cent theory). 

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