In Situ Anodically Oxidized BMIm-BF₄: A Safe and Recyclable BF₃ Source

Abstract

The anodic oxidation of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIm-BF 4 ) efficiently generates BF 3 from BF 4 – . This Lewis acid, strongly bound to the ionic liquids, can be efficiently used in classical BF 3 -catalyzed reactions. We demonstrated the BF 3 /BMIm-BF 4 reactivity in four reactions, namely, a domino Friedel–Crafts/lactonization of phenols, the Povarov reaction, the Friedel–Crafts benzylation of anisole, and the multicomponent synthesis of tetrahydro-11 H -benzo[ a ]xanthen-11-ones. In comparison with literature data using BF 3 -Et 2 O in organic solvents, in all the presented cases, analogous or improved results were obtained. Moreover, the noteworthy advantages of the developed method are the in situ generation of BF 3 (no storing necessity) in the required amount, using only the electron as redox reagent, and the recycling of BMIm-BF 4 for multiple subsequent runs.

Interfacial Electrochemistry-Induced Detachable Adhesives with Ultra-High Bonding Strength and Detaching Efficiency

“…Crucially, a sharp ion current peak at m / z = 2 is observed revealing that hydrogen gas (H 2 ) is generated during the cathodic reduction (Figure C). The enriched [BMIM] + around the cathode get electrons, and the C 2 of the imidazole ring is reduced into saturated carbon (insert in Figure C), thereby releasing H 2 . − In addition, ion current peaks assigned to the molecular ion of fluorochemicals are monitored during the IEMS measurement. For instance, the ion current peaks at m / z = 20 and m / z = 34 can be assigned to the molecular ion of HF and CH 3 F; and the ion current peak at m / z = 69 can be assigned to the fragment ions of CF 3 + .…”

“…These findings suggest that fluorine gas (F 2 ) is generated during the electrolytic process, which originated from anodic oxidation (Figures D–F and Table S3). The organic anion (BF 4 – ) enriched around the anode loses electrons and is oxidized into BF 3 and F 2 . − As a result, the fluorochemicals are generated by a combination of H 2 or hydrocarbons compounds with the formed reactive F 2 .…”

Electrochemical Bottom-Up Synthesis of Chiral Carbon Dots from L-Proline and Their Application as Nano-Organocatalysts in a Stereoselective Aldol Reaction

“…Due to our experience in asymmetric organocatalytic methodologies [34][35][36][37][38][39] as well as in the development of innovative electrochemical synthetic methodologies [40][41][42][43][44][45], we envisioned the combination of electrochemical synthesis of CCDs to be used as sustainable, green and biocompatible nano-organocatalysts to promote stereoselective reactions (Scheme 1b). We decided to decorate the CDs with L-proline as this amino acid is frequently used in asymmetric organocatalysis.…”

Ionic Liquids as Organocatalysts for Nucleophilic Fluorination: Concepts and Perspectives

“…Significantly enhanced reactivity and selectivity have also been observed in concerted reactions such as nucleophilic substitution reactions in ionic liquids [ 14 , 15 , 16 ]. By combining a variety of cations and anions with characteristic structures, it is possible to tailor-make task-specific ILs with desirable properties for specific chemical reactions [ 15 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 ].…”