Electrogenerated N‐Heterocyclic Olefins: Stability and Catalytic Ability. Issue 4 (14th December 2017)

• Record Type: Journal Article
• Authors: Feroci, Marta; Chiarotto, Isabella; Orsini, Monica; Pandolfi, Fabiana; Zane, Daniela; Inesi, Achille
• Is Part Of: ChemElectroChem. Volume 5:Issue 4(2018)
• Page Start: 651
• Page End: 658
• Publication Date: 2017-12-14
• Subjects: N-heterocyclic olefin -- N-heterocyclic carbene -- ionic liquids -- cyclic voltammetry -- stability; Electrochemistry -- Periodicals; 541.37
• DOI: 10.1002/celc.201700992
• Languages: English
• ISSNs: 2196-0216

Abstract

Abstract: N‐Heterocyclic olefin (NHO) can be generated by simple cathodic reduction of BDMImBF4 ‐DMF solution or neat BDMImBF4 (BDMImBF4 =1‐butyl‐2, 3‐dimethyl‐1 H ‐imidazolium tetrafluoroborate; DMF=dimethylformamide). In the latter case, the use of any organic solvent and chemical base is avoided. To prove the presence of NHO, its adduct with benzaldehyde was isolated. The electrochemical behavior of NHO is very similar to that of the corresponding N‐heterocyclic carbene (NHC, from 1‐butyl‐3‐methyl‐1 H ‐imidazolium tetrafluoroborate), showing that it is electroactive at the anode, and this peculiarity can be exploited to verify its presence in a solution. The main difference between NHO and NHC is in the nucleophilic site (exocyclic for NHO, endocyclic for NHC). Electrogenerated NHO stability (evaluated by cyclic voltammetry) and its catalytic ability (evaluated in the transesterification reaction) were compared with those of electrogenerated NHC. Abstract : Not only NHC ! The cathodic reduction of a 2‐methylimidazolium cation led to the formation of the corresponding N‐heterocyclic olefin, with an exocyclic double bond. This species, more stable of the corresponding N‐heterocyclic carbene (NHC), is a very good organocatalyst in transesterification reactions.