Kinetic compensation effect: discounting the distortion provoked by accidental experimental errors in the isokinetic temperature value

Random experimental errors are known to provoke the appearance of false isokinetic enthalpy–entropy relationships under some circumstances. In this contribution, it is shown that the observation of a false error-caused isokinetic plot, with a slope close to the mean working temperature ( T m ), does not necessarily preclude the occurrence of a real isokinetic temperature ( T ik ) that might be quite different from T m , for that particular homologous reaction series. However, since accidental errors cause a shift in the value of parameter T ik toward that of T m , different numerical simulation methods have been tried to discount this effect and so obtain the most probable (extrapolated) value of T ik . The method leading to the best results was that of shifting the maximum probability curve for each reaction series until it matched the experimental point (defined by both the T ik value and the activation enthalpy mean fitting error). Finally, the applicability of this method has been checked out for 17 reaction families selected from chemical bibliographic sources. According to the results found in this study, when the experimental isokinetic temperature is higher than the mean working temperature ( T ik,exp > T m ) the most probable value should be looked for in the high temperature range ( T ik,sim > T ik,exp ), and when T ik,exp < T m in the low temperature range ( T ik,sim < T ik,exp ). Moreover, the best parameter to predict the relative error that must be allowed to T ik,sim is the correlation coefficient of the experimental compensation plot. Graphic abstract