Year: 2026
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Lewis acidic chloroaluminate ionic liquid diluted in dichloromethane catalyzes the disproportionation of alkanes, such as isopentane, via carbenium ions in a reaction readily initiated by carbenium ion precursors such as tert -butyl chloride (TBC). The carbenium ion-AlCl 4 – ion-pairs stabilized by the ionic liquid-dichloromethane solution are the key intermediates in two distinctive kinetic regimes, i.e., a transient regime (0–5 min) and a steady-state regime (after 5 min). The transient regime constitutes the majority of isopentane conversion and is governed by the initial carbenium ion concentration. In the steady-state regime, disproportionation occurs at a considerably lower rate, affected by the carbenium ion concentration, the concentration of the ionic liquid, and the reaction temperature. The formation of alkenes observed in the 1 H NMR spectra of the reacting substrates, along with the DFT calculations, suggests that deprotonation of carbenium ion-pairs reduces their concentration, decreasing, in turn, the reaction rate. Kinetic modeling indicates that the transient regime is significantly controlled by the hydride transfer ( k HT ) and the deprotonation rate constants ( k DP ), while the steady-state regime is additionally influenced by the alkene protonation rate constant ( k –DP ). The overall activation energy of the reaction at the steady state, expressed as E a,steady-state regime = E a,HT – E a,DP + E a,–DP, was 54 kJ/mol. The reaction mechanism and the kinetics highlight the potential of Lewis acid-catalyzed conversions of hydrocarbons under remarkably mild conditions.
DOI: 10.1021/jacs.6c03060
Language: English
Subfield: Catalysis
Field: Chemical Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: G1118031844, G1286236842, G1286251239, G1677143136, G1736462507, G2037563265, G2141673615, G2339781709, G2643203774, G30714459, G3083819904, G3309974852, G3466678926, G3496119864, G4189126877, G419881185, G4501827968, G4886642085, G498139845, G5076365615, G6064526139, G613759197, G6261433946, G650090426, G6652958823, G7603878958, G865198864, G969889393
OpenAlex ID: W7165052595