Solvation at keto-enol, acid-base and extraction equilibria and Meyer's equation

It is shown that the equation proposed by K. Meyer [K.H. Meyer, Berichte. 45(1912) 2843-2864] as empirical for constants of keto-enol equilibrium in various solvents is in fact a simple consequence of the additivity principle for Gibbs energies of molecules' solvation and hence is applicable to many types of chemical reactions. The examples of fulfillment of Meyer's equation in cases of keto-enol, acid-base and extraction equilibria are brought, and solvent parameters for each discussed example are determined. For the case of keto-enol equilibria with a possibility of intramolecular H-bond in enol form such parameters for 36 solvents are determined and compared with polarity parameters ET.