Merging of E2 and E1cb Reaction Mechanisms: A Combined Theoretical and Experimental Study

Abstract

By combining the results of kinetic measurements with DFT calculations we provide a clear-cut evidence of the merging between the E2 and E1cb reaction mechanisms for a large series of leaving groups. Our results solve a long-debated issue in chemical reactivity with profound implications both

Insights into the elimination mechanisms employed for the degradation of different hexachlorocyclohexane isomers using kinetic isotope effects and docking studies

“…It has been commonly accepted that large leaving group‐KIEs accompanied by large deuterium KIEs are a strong indication of synchronous E2 mechanism. However, not all systems studied present such clear‐cut scenarios . KIEs, however, calculated in this work indicate that they can be useful tools in substantiating findings from docking studies as well as transition state structures obtained for pure HCH isomers.…”

DFT Investigation of Ligand-Based Reduction of CO2 to CO on an Anionic Niobium Nitride Complex: Reaction Mechanism and Role of the Na+ Counterion

“…Vibrational frequency analysis was performed on all the transition state structures and minima of the potential energy surface. The evaluation of Gibbs free energy is calculated by following a procedure similar to those employed for the evaluation of absolute p K a ’s. − , Following a thermodynamic cycle, the Gibbs free energy in solution of species i ( G i solv ) is defined as G i solv = G i vac + Δ G solv , where G i vac is the free energy of species i in vacuo and Δ G solv is the free energy of solvation. G i vac is computed at the geometry optimized in vacuo, followed by frequency calculations to take into account the vibrational contribution to the total partition function.…”

“…To gain insight into the energetics and reaction mechanism of this catalytic cycle, in this work we computationally investigate, by means of density functional theory calculations, the free energy reaction profile of the whole catalytic process, employing a previously developed computational setup well-suited to investigate organic and organometallic reactivity. − In particular, we point our attention to step b, involving the reaction between [Na][O 2 C-1] and Ac 2 O to lead to the [Me-2] product. This crucial step can indeed proceed either (i) via a stepwise mechanism involving a reaction intermediate, [I-1] in Scheme , as was proposed in ref , that subsequently evolves via an intramolecular reaction to give the [Me-2] product or (ii) via a concerted mechanism leading directly to the product (Scheme ).…”

Regioselective Synthesis of 1,4,5‐Trisubstituted‐1,2,3‐Triazoles from Aryl Azides and Enaminones

“…In the presence of the base, the retro‐aza‐Michael reaction (elimination of aniline), is promoted and the stable final 1,4,5‐trisubstituted‐1,2,3‐triazole is obtained through a cascade process. The transition state corresponding to the elimination of aniline ( TSe1 ) according to an E1 CB mechanism showed a barrier of 7.1 kcal/mol, confirming that the cycloadditions step is the rate‐limiting one (for details see SI). These results are in good agreement with the observed results although, admittedly, there is an additional favoring effect exerted by the ionic liquid.…”