Determination of Δ<i>H</i>^≠ and Δ<i>S</i>^≠ by simultaneous ¹H and ¹³C dynamic n.m.r. studies: Importance of the accuracy of temperature measurement

Abstract

Abstract From Δ G Tc ≠ values obtained by 1 H and 13 C dynamic nuclear magnetic resonance studies of the same dynamic process, it is possible to estimate Δ H ≠ and Δ S ≠ . Nevertheless, the accuracy of the temperature measurement is a factor which limits the applicability of this method. A very simple procedure for calibrating the usual temperature sensors is described, which can be applied to all types of n.m.r. probes. By the use of this procedure it is possible to measure coalescence temperatures in 1 H and 13 C n.m.r. with such an accuracy that Δ S ≠ can be effectively determined from the difference between Δ G Tc ≠ values.