N-heterocyclic carbene-mediated oxidation of copper(I) in an imidazolium ionic liquid

Shah, Sameera; Pietsch, Tobias; Ruck, Michael

doi:10.1515/znb-2022-0305

“…Moreover, imidazolium‐based ILs can be deprotonated at the C 2 position of the imidazolium ring to N ‐heterocyclic carbenes (NHC, imidazole‐2‐ylidenes) [43] . To investigate whether this (weak) acidity is essential for the dissolution of La 2 O 3 , we performed the reaction under the same conditions but with IL‐cations that are not Brønsted acids.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, imidazolium-based ILs can be deprotonated at the C 2 position of the imidazolium ring to N-heterocyclic carbenes (NHC, imidazole-2-ylidenes). [43] To investigate whether this (weak) acidity is essential for the dissolution of La 2 O 3 , we performed the reaction under the same conditions but with IL-cations that are not Brønsted acids. These were the chloridoaluminates of alkylammonium [N 4444 ] + , alkylphosphonium [P 66614 ] + , pyridinium [NBuPy] + , and benzylmethyl-imidazolium [BzMIm] + as well as of butyl-dimethylimidazolium [BDMIm] + , which is methylated at the C 2 position of the imidazolium ring.…”

Section: Methodsmentioning

confidence: 99%

Facile Synthesis of Anhydrous Rare‐Earth Trichlorides from their Oxides in Chloridoaluminate Ionic Liquids

Shah,

Pietsch,

Ruck

2023

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Wide applications of anhydrous rare‐earth (RE) trichlorides RECl3 in organometallic chemistry, for the synthesis of optical and magnetic materials, and as catalysts require a facile approach for their synthesis. The known methods use or produce toxic substances, are complicated and have limited reliability and upscaling. It has been shown that task‐specific ionic liquids (ILs) can dissolve many metal oxides without special reaction conditions at moderate temperature, making the metals accessible to downstream chemistry. Using imidazolium chloridoaluminate ILs, pure crystalline anhydrous RECl3 (RE=La−Nd, Sm−Dy) can be synthesized in one step from RE oxides in high yield. The Lewis acidic IL acts as solvent and reaction partner. The by‐product [Al4O2Cl10]2−, which was detected spectroscopically, remains in solution. The reacted IL can be removed quantitatively by washing. ILs with various imidazolium cations and AlCl3 content and the effect of temperature and reaction time were tested.

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“…The proton at the C 2 -position of the ring is acidic and can be abstracted by a base. This generates an N-heterocyclic carbene (imidazole-2-ylidene), which can be functional in organo-catalytic reactions [21,22]. Imidazolium acetate ILs have been used to dissolve biomass, e.g., cellulose, and to store CO 2 [23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Reactivity of Rare-Earth Oxides in Anhydrous Imidazolium Acetate Ionic Liquids

Shah

¹

,

Pietsch

²

,

Herz

³

et al. 2023

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Rare-earth metal sesquioxides (RE2O3) are stable compounds that require high activation energies in solid-state reactions or strong acids for dissolution in aqueous media. Alternatively, dissolution and downstream chemistry of RE2O3 have been achieved with ionic liquids (ILs), but typically with additional water. In contrast, the anhydrous IL 1-butyl-3-methylimidazolium acetate [BMIm][OAc] dissolves RE2O3 for RE = La–Ho and forms homoleptic dinuclear metal complexes that crystallize as [BMIm]2[RE2(OAc)8] salts. Chloride ions promote the dissolution without being included in the compounds. Since the lattice energy of RE2O3 increases with decreasing size of the RE3+ cation, Ho2O3 dissolves very slowly, while the sesquioxides with even smaller cations appear to be inert under the applied conditions. The Sm and Eu complex salts show blue and red photoluminescence and Van Vleck paramagnetism. The proton source for the dissolution is the imidazolium cation. Abstraction of the acidic proton at the C2-atom yields an N-heterocyclic carbene (imidazole-2-ylidene). The IL can be regenerated by subsequent reaction with acetic acid. In the overall process, RE2O3 is dissolved by anhydrous acetic acid, a reaction that does not proceed directly.

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Facile Synthesis of Anhydrous Rare‐Earth Trichlorides from their Oxides in Chloridoaluminate Ionic Liquids

Shah,

Pietsch,

Ruck

2023

Angewandte Chemie

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0

View full text Add to dashboard Cite

Wide applications of anhydrous rare‐earth (RE) trichlorides RECl3 in organometallic chemistry, for the synthesis of optical and magnetic materials, and as catalysts require a facile approach for their synthesis. The known methods use or produce toxic substances, are complicated and have limited reliability and upscaling. It has been shown that task‐specific ionic liquids (ILs) can dissolve many metal oxides without special reaction conditions at moderate temperature, making the metals accessible to downstream chemistry. Using imidazolium chloridoaluminate ILs, pure crystalline anhydrous RECl3 (RE=La−Nd, Sm−Dy) can be synthesized in one step from RE oxides in high yield. The Lewis acidic IL acts as solvent and reaction partner. The by‐product [Al4O2Cl10]2−, which was detected spectroscopically, remains in solution. The reacted IL can be removed quantitatively by washing. ILs with various imidazolium cations and AlCl3 content and the effect of temperature and reaction time were tested.

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N-heterocyclic carbene-mediated oxidation of copper(I) in an imidazolium ionic liquid

Cited by 3 publications

References 53 publications

Facile Synthesis of Anhydrous Rare‐Earth Trichlorides from their Oxides in Chloridoaluminate Ionic Liquids

Facile Synthesis of Anhydrous Rare‐Earth Trichlorides from their Oxides in Chloridoaluminate Ionic Liquids

Reactivity of Rare-Earth Oxides in Anhydrous Imidazolium Acetate Ionic Liquids

Facile Synthesis of Anhydrous Rare‐Earth Trichlorides from their Oxides in Chloridoaluminate Ionic Liquids

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