Kinetic Study of Liquid-Phase Esterification with Sulfonic Acid Cation-Exchange Resin of the Macroreticular Type. II. Solvent Effects on Resin Catalysis

Article abstract of DOI:10.1246/bcsj.60.1975

The rates of the esterification of octanoic acid with 1-butanol catalyzed by macroreticular sulfonated ion-exchange resin in the presence of various organic solvents and water were measured by the use of a batch reactor.The solvent effects on the rate were investigated by applying the heterogeneous-pseudohomogeneous reaction mechanism.From these results, it was found that the effects can be quantitatively estimated by means of the magnitude of the equilibrium constants, K^(S)_sol, for the solvent-separated ion-pair formations, which are due to the interaction of the sulfo groups in the resin with the solvents.The correlations of the K^(S)_sol value with the physical properties, μ end ε; the solvatochromic parameters ?*, α, and β, and Gutmann's parameters, AN_E and DN_B, have been examined by using linear regession analysis methods.The results of the correlations in which the protic solvents have been excluded suggest that the positions of the equilibria of solvent-separated ion-pair formations depend mainly on the electron-donor property of the solvents; that is to say, the solvents with a strong donor property diminish the number of un-ionized sulfo groups which act as catalytic species for the heterogeneous reaction.