A simple evaluation of an assumed second-order reaction with equimolar reactants 3 and 5 is possible with the plot of 1/[3] vs. t. The plots show a very good linear dependence up to conversions of ~60 % (see SI Figure ) confirming that the reaction of the terminal groups of 3 and 5 follows over a wide range the kinetics of a second-order reaction (see Table ). In a second approach, the data on the reaction kinetics were analyzed in two steps. First, the low time limit of the ratio of the concentrations [3]/[3]0 of the reactive groups was fit to a modified form of equation ( ) in the form of