Specificities of application of the supermolecule method to the calculation of reaction mechanisms in a protonodonor medium. Ethylene carbonate aminolysis in methanol

Understanding the Reshaping of Fluorinated Polyester Vitrimers by Kinetic and DFT Studies of the Transesterification Reaction

“…One recent contribution has specifically addressed a model system of the metal‐catalyzed transesterification in vitrimers [19e] . A comparative investigation of the direct and two‐step pathways, with extensive analysis of the H‐bond chain assistance, has been presented for a mechanistically related reaction (the carbonate ester amination), [20] yielding activation barriers that are highly dependent on the number of proton relay molecules in the chain. Since the present investigation only aims at examining the relative effect of the F substitution, which presumably is mostly expressed at the electronic level, we have opted to limit the investigation to the two step‐pathway.…”

Enhanced aminolysis of cyclic carbonates by β-hydroxylamines for the production of fully biobased polyhydroxyurethanes

“…A rationalization of these differences requires a detailed analysis of the reaction mechanism. The EC aminolysis has previously been analyzed by computational methods by Zabalov et al [37][38][39] Two main reactant and n-BuOH solvent). 37 A subsequent thorough analysis of the effect of several MeOH molecules (up to six) for both concerted and stepwise mechanisms revealed the presence of several distinct pathways with similar activation barrier and a complex role of the H-bonding solvent, including the possible stabilization of zwitterionic intermediates (e.g.…”

“…EC-NHR -•••H 2 X + ). 39 Finally, a recent contribution detailed the catalytic action of guanidine as H-X for the EC aminolysis by MeNH 2 in DMSO. 38 The latter study underlines the assistance of the DMSO solvent for the stabilization of cyclic intermediates and transition states, even though it cannot be directly involved in proton transfer chains.…”

“…We wish to underline that the purpose of this DFT investigation was not to quantitatively reproduce the relative rates and activation barriers, because the previously published work has demonstrated that this requires the explicit inclusion of several solvent molecules and a lengthy investigation of a large number of pathways. [37][38][39] We only wished to highlight the key role of the β-OH substituent in opening a single amine molecule pathway for the reaction. Therefore, no solvent molecules (CHCl 3 ) were explicitly included in the calculations and the effect of the solvent was only accounted for by the inclusion of a polarizable continuum.…”

“…We have comparatively analyzed three reaction pathways: i) the two-molecule (k 2 ) pathway for the alkylamine; ii) the two-molecule pathway for the alkoxylamine; iii) the one-molecule pathway (k 1 ) for the alkoxylamine. The first one only serves as a reference since they do not present unprecedented features relative to the work of Zabalov et al [37][38][39] The starting reactant complex features two H The barrier difference between the one-molecule pathway (Figure 5, 24.8 kcal mol -1 ) and the twomolecule pathway (Figure 4, 11.4 kcal mol -1 ) appears too large when considering that both pathways are competitive. In the real system, this difference may be attenuated by specific stabilizing effects by solvent molecules.…”