A comparison of the rate constants for the reaction using M19 and DABCO shows that the rate constant for the reaction with M19 is 7.8 times larger than the one for the reaction with DABCO. From the Eyring equation, we calculate that the Gibbs energy of activation at 22 • C is 1.12 kcal/mol lower for the reaction with M19 than for the reaction with DABCO. This agrees well with the previously calculated value of 2.40 kcal/mol. Furthermore, 54 % conversion could be reached after 7 h reaction time using M19 as catalyst compared to 16 % using DABCO in deuterated solvent. As shown by Plata and Singleton , significantly higher conversion is reached in undeuterated solvent which would follow the predicted conversion in Figure yielding 48 % and 87 % conversion after 24 h for the reaction with DABCO and M19, respectively.