Fig. 6. Optimizing the kinetic curves' linearity by catalyzing the Michael addition using K2CO3, UPypent5, and various amounts of NaPy 1. (a) Schematic depiction of the Michael addition between Malref3 and UPypent5. NaPy 1 and the various types of UPy dimers formed between UPypent5 and UPyproduct6 all function as phase-transfer catalyst. (b) Simulated kinetic curves of the reaction between UPypent5 (c = 4 mM), K2CO3 (c = 36 mM) and varying amounts of NaPy 1. The residuals of a linear fit up to 75% conversion were calculated, showing that the most linear kinetics can be obtained using a mixture of NaPy 1 (≈5 mM), Malref3 (4 mM), UPypent5 (4 mM) and K2CO3 (36 mM). The residuals were normalized to the number of simulated points up to 75% conversion, to enable a concentration dependent comparison. (c) The conversion of the K2CO3 catalyzed Michael addition (c = 36 mM) between equimolar mixtures of Malref3 (c = 4 mM), UPypent5 (c = 4 mM), and varying amounts of NaPy 1 (symbols). The reactions were performed in CDCl3 at room temperature, all components were combined simultaneously. The lines are to guide the eye. The inset shows the residuals of a linear fit of the data point up to 75% conversion for the reactions performed using UPypent5, NaPy 1 and Malref3, as well as the reactions performed using UPy 2, NaPy 1, Malref3 and Pentref4.
