Free <i>N</i>‐heterocyclic carbenes from Brønsted acidic ionic liquids: Direct detection by electrospray ionization mass spectrometry

Salvitti, Chiara; Pepi, Federico; Managò, Marta; Bortolami, Martina; Michenzi, Cinzia; Chiarotto, Isabella; Troiani, Anna; Petris, Giulia de

doi:10.1002/rcm.9338

Cited by 6 publications

(2 citation statements)

References 59 publications

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“…Published literature [29][30][31][32][33][34] signifies that there is a relationship between the SPAB of ILs on catalytic activity. [bmim][OHB] with the lowest anion-anion aggregation provided excellent yields.…”

Section: Relationship Of Spab and Thermal Stability With Catalytic Ac...mentioning

confidence: 99%

Synthesis of Benzoate‐Based Functionalized Ionic Liquids: Relationship between Supramolecular aggregation behavior and Catalytic activity in Phenyl Pyrimidines Derivatives

Naveed Javed,

Muhammad,

Riaz

et al. 2023

ChemistrySelect

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This study reports synthesizing and characterizing imidazolium‐based ionic liquids (ILs) using substituted benzoates as anions. Thermal stability of ILs described using thermogravimetric analysis (TGA). One inherent property of ILs is aggregates or cluster formation due to supramolecular interactions. The supramolecular interaction in synthesized ILs has been studied through Electrospray ionization mass spectrometry (ESI‐MS). The potential of ILs as organic catalysts is investigated in multicomponent reaction (MCR) using urea, malononitrile, and different aromatic aldehydes to prepare phenyl pyrimidines derivatives. The results demonstrate that catalysis with ILs effectively reduces reaction time and enhances yield. ILs entities are hypothesized to form new assemblies with reactive moieties of reactants through supramolecular interactions. The ILs can be reused and recycled.

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Section: Relationship Of Spab and Thermal Stability With Catalytic Ac...mentioning

confidence: 99%

Synthesis of Benzoate‐Based Functionalized Ionic Liquids: Relationship between Supramolecular aggregation behavior and Catalytic activity in Phenyl Pyrimidines Derivatives

Naveed Javed,

Muhammad,

Riaz

et al. 2023

ChemistrySelect

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“…However, recent work suggests spontaneous NHC formation in imidazolium acetate ILs, despite the acetate ion being only a weak/mild base. For example, several NHC-catalyzed reactions have been found to occur in the ILs [EMIM + ][OAc – ] and [BMIM + ][OAc – ], such as benzoin condensation, formation of imidazol-2-thiones, polymerization of epoxy resins, and others, which provides indirect evidence. − While mass spectrometry measurements show existence of NHCs in vaporized samples of [EMIM + ][OAc – ] and related ILs, , the vapor phase may not be representative of the liquid due to the expected large contribution of ion solvation to the reaction free energy. No direct experimental observation of NHC formation in the liquid phase has been made, as their inherently short lifetime makes such characterization challenging.…”

Section: Introductionmentioning

confidence: 99%

N-Heterocyclic Carbene Formation in the Ionic Liquid [EMIM⁺][OAc^–]: Elucidating Solvation Effects with Reactive Molecular Dynamics Simulations

Stoppelman

McDaniel

2023

J. Phys. Chem. B

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Recent experimental and theoretical work has debated whether N-heterocyclic carbenes (NHCs) are natively present in imidazolium-based ionic liquids (ILs) such as 1-ethyl-3-methylimidazolium acetate ([EMIM+][OAc–]) at room temperature. Because NHCs are powerful catalysts, determining their presence within imidazolium-based ILs is important, but experimental characterization is difficult due to the transient nature of the carbene species. Because the carbene formation reaction involves acid–base neutralization of two ions, ion solvation will largely dominate the reaction free energy and thus must be considered in any quantum chemical investigation of the reaction. To computationally study the NHC formation reaction, we develop physics-based, neural network reactive force fields to enable free energy calculations for the reaction in bulk [EMIM+][OAc–]. Our force field explicitly captures the formation of NHC and acetic acid by deprotonation of a EMIM+ molecule by acetate and in addition describes the dimerization of acetic acid and acetate. Using umbrella sampling, we compute reaction free energy profiles within the bulk IL and at the liquid/vapor interface to understand the influence of the environment on ion solvation and reaction free energies. Compared to reaction of the EMIM+/OAc– dimer in the gas phase, the bulk environment destabilizes formation of the NHC as expected due to the large ion solvation energies. Our simulations reveal a preference for the product acetic acid to share its proton with an acetate in solution and at the interface. We predict NHC content in bulk [EMIM+][OAc–] to be on the order of parts-per-million (ppm) levels, with order-of-magnitude enhancement of NHC concentration at the liquid/vapor interface. The interfacial enhancement of NHC content is due to both poorer solvation of the ionic reactants and solvophobic stabilization of the neutral NHC molecule at the liquid/vapor interface.

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Photo‐activated Carbon dots (CDs) as Catalysts in the Knoevenagel Condensation: A Mechanistic Study by Dual‐Mode Monitoring via ESI‐MS

Cosentino,

Michenzi,

Di Noi

et al. 2024

ChemPlusChem

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Carbon dots (CDs) obtained from 5‐(hydroxymethyl)furfural (5‐HMF) were activated by a 365 nm‐UV irradiation source and employed in the Knoevenagel condensation to investigate their photocatalytic mechanism. To this end, electrospray ionization mass spectrometry (ESI‐MS) was used to monitor the time progress of the condensation and follow the formation of the final product in positive and negative ion modes at once. The intervention of the superoxide radical anion in the photocatalytic mechanism of CDs was highlighted.

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Free N‐heterocyclic carbenes from Brønsted acidic ionic liquids: Direct detection by electrospray ionization mass spectrometry

Cited by 6 publications

References 59 publications

Synthesis of Benzoate‐Based Functionalized Ionic Liquids: Relationship between Supramolecular aggregation behavior and Catalytic activity in Phenyl Pyrimidines Derivatives

Synthesis of Benzoate‐Based Functionalized Ionic Liquids: Relationship between Supramolecular aggregation behavior and Catalytic activity in Phenyl Pyrimidines Derivatives

N-Heterocyclic Carbene Formation in the Ionic Liquid [EMIM⁺][OAc^–]: Elucidating Solvation Effects with Reactive Molecular Dynamics Simulations

Photo‐activated Carbon dots (CDs) as Catalysts in the Knoevenagel Condensation: A Mechanistic Study by Dual‐Mode Monitoring via ESI‐MS

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Free N‐heterocyclic carbenes from Brønsted acidic ionic liquids: Direct detection by electrospray ionization mass spectrometry

Cited by 6 publications

References 59 publications

Synthesis of Benzoate‐Based Functionalized Ionic Liquids: Relationship between Supramolecular aggregation behavior and Catalytic activity in Phenyl Pyrimidines Derivatives

Synthesis of Benzoate‐Based Functionalized Ionic Liquids: Relationship between Supramolecular aggregation behavior and Catalytic activity in Phenyl Pyrimidines Derivatives

N-Heterocyclic Carbene Formation in the Ionic Liquid [EMIM+][OAc–]: Elucidating Solvation Effects with Reactive Molecular Dynamics Simulations

Photo‐activated Carbon dots (CDs) as Catalysts in the Knoevenagel Condensation: A Mechanistic Study by Dual‐Mode Monitoring via ESI‐MS

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N-Heterocyclic Carbene Formation in the Ionic Liquid [EMIM⁺][OAc^–]: Elucidating Solvation Effects with Reactive Molecular Dynamics Simulations