INFINITE DILUTION ACTIVITY-COEFFICIENTS FROM UNIFAC MODEL FOR 2-CHLORO-2-METHYLPROPANE IN BINARY-MIXTURES OF ALCOHOLS - APPLICATION TO THE MECHANISTIC STUDY OF SOLVOLYTIC REACTIONS

In this work infinite dilution activity coefficients (gamma(i)nfinity) of 2-chloro-2-methylpropane (tert-BuCl) in solvent mixtures of methan ol/ethane-1,2-diol, ethanol/ethane-1,2-diol, and 2-methoxyethanol/etha ne-1,2-diol have been calculated using the UNIFAC group-contribution m odel. For each system nine different compositions of the solvent mixtu res were considered. The modification of the Flory-Huggins term in the combinatorial equation and the group-contribution parameters from the vapor-liquid equilibrium parameter table were used. These values toge ther with the Gibbs energies of activation (Delta(double dagger) G), o btained from the new experimental rate constant values of the solvolyt ic reactions of the same substrate in the binary alcoholic mixtures, a llow the analysis of the solvent effect during the activation process, by means of the contributions of the initial state and the transition state.