Anomalous temperature dependence of the kinetic isotope effect in hydrogen exchange between cumene and dimethyl sulfoxide catalyzed by potassium tert-butoxide

The authors report on yet another example of reaction with an anomalous temperature dependence of the kinetic isotope effect. While studying the kinetics of hydrogen exchange in partially tritiated cumene (cumene-..cap alpha..-H,T) with perdeuterodimethyl sulfoxide (DMSO), catalyzed by potassium tert-butoxide, they established that the k/sup H//k/sup T/ values increase with increase in temperature. They supposed that of the observed anomalous temperature dependence of the kinetic isotope effect is use to features of the mechanism in the elementary event of the proton transfer reaction or to features of the potassium tert-butoxide-DMSO catalytic system, since it is known that potassium tert-butoxide undergoes solvolysis in DMSO with the formation of the potassium DMSO salt (KCH/sub 2/SOCH/sub 3/). its participation in hydrogen exchange in cumene may be the reason for the anomalous temperature dependence of the kinetic isotope effect. They intend to investigate these reasons.