Fig. 2. Experimental and computational data related to the Michael addition catalyzed by NaPy and K2CO3. (a) Schematic depiction of the NaPy 1 catalyzed Michael addition between Malref3 and Pentref4. (b) The conversion of the Michael addition between Malref3 (c = 4 mM) and Pentref4 (c = 4 mM) in the presence of various combinations of K2CO3 (c = 36 mM), NaPy 1 (c = 8 mM) and additionally added product (c = 10 mM, symbols) and the best fits of the kinetic model based on bimolecular mass action kinetics (lines, lines with identical color belong to the same reaction, with the only difference that they are dashed when additional Michael product was added at the start of the reaction). The results show that the product does not significantly influence the rate of the NaPy catalyzed reaction. The reactions were performed in CDCl3 at room temperature, all components were combined simultaneously. (c) Optimized geometry as obtained from DFT calculations on two NaPys complexing K2CO3, showing how the nitrogen lone-pairs, aromatic rings and carbonyl oxygens of each NaPy coordinate to a potassium ion while the carbonate anion binds the two potassium ions together. (d) Optimized geometry as obtained from DFT calculations on the Michael product complexing K2CO3. (e) Schematic of the kinetic mass action model including the background reaction, autocatalysis, and NaPy catalysis. The formation of the product·K2CO3 and diNaPy·K2CO3 complexes was not included in the model as it is not required to obtain a proper fit of the data, instead their formation is viewed as being instantaneous.
