Solvent and Steric Effects on the Solvolysis of Polyvinylsulfonic Acid Esters

Abstract

Abstract The solvolysis of ethanesulfonic acid esters followed closely first-order kinetics, while the case of polyvinylsulfonic acid esters gave strongly-curved first-order plots according to the solvent composition. With a high acetone content, the solvolysis rates of polymeric sulfonic esters decreased gradually with the lapse of time, while in a high water content, the solvolysis was suppressed at the beginning of the reaction but was accelerated remarkably with the reaction time. The former finding indicates the release from the steric congestion which contributed to the initial rate enhancement, while the latter indicates the aggregation of the polymer molecules owing to their strong hydrophobic character. The solvolysis rates, kp, for polymeric sulfonic esters were much greater than those, km, for monomeric analogs in all cases except isopropyl and n-butyl esters in 20% aqueous acetone. The relative rate (kp/km) increased with an increase in the acetone content and was apparently greater with the methyl ester than with the other esters, and the value of (kp/km) in relation to the methyl ester in 80% acetone content reached 15. Furthermore, it was found that the proton catalysis by the neighboring sulfonic acid formed on the lapse of reaction time was absent, and also that the salt effect was negligibly small.