Reduction of Aromatic Compounds in Organic Chloroaluminate Melts: I . Phenazine

Abstract

The electroreduction of phenazine in basic mixtures of A1C13 and 1-ethyl-3-methyl-lH-imidazolium chloride (EMIC) (44.4 mole percent A1C13) has been investigated by electrochemical and spectroscopic techniques. Initial results suggested that the reduction of phenazine proceeded through a two-electron process coupled with two protonations to form dihydrophenazine. However, further investigation, using authentic dihydrophenazine, indicated that this reduction product was not the result of proton exchange reactions but rather a chloroaluminate species may be acting as the acidic entity in this liquid. The use of neat 1-ethyl-3-methyl-lH-imidazolium hydrogen dichloride (ImHC12) and mixtures of A1C13 and 1,2dimethyl-3-propyl-lH-imidazolium chloride (DMPIC) as solvents for electrochemical investigations of dissolved organic substrates is also reported.

Molecular Design of Fused-Ring Phenazine Derivatives for Long-Cycling Alkaline Redox Flow Batteries

“…34−37 Phenazine and its derivatives have been widely used as broad-spectrum antibiotics. 38 It has been found that phenazine shows reversible redox properties in water−DMF mixtures, 39,40 but its insolubility in water hinders the application in ARFBs. Through the grafting of triethylene glycol (TEG) linkers or sulfonate groups, the solubility of phenazine derivatives can be increased to different extents.…”

“…The degradation mechanism of organic molecules in nonaqueous system has been widely studied for many years, − while the capacity fade mechanism of organic redox-active species in aqueous systems has attracted rising attention over the last 5 years. − To date, the redox reversibility of water-soluble organic molecules has been successfully extended to varying degrees. − Phenazine and its derivatives have been widely used as broad-spectrum antibiotics . It has been found that phenazine shows reversible redox properties in water–DMF mixtures, , but its insolubility in water hinders the application in ARFBs. Through the grafting of triethylene glycol (TEG) linkers or sulfonate groups, the solubility of phenazine derivatives can be increased to different extents. , Meanwhile, the effects of different functional groups of phenazine derivatives on the aqueous solubility, electrochemical redox properties, and cycling stability are waiting to be further explored.…”

“…To investigate the pH-dependent structural transformation behaviors of these phenazine derivatives in aqueous solution, UV–vis spectra were measured at different pH values, as shown in Figure . Moreover, the TDDFT-simulated light absorption lines of these molecules were obtained by calculating the energy levels of the HOMO (highest occupied molecular orbital) and LUMO (lowest occupied molecular orbital), , as shown in the insets of Figure b,d,f.…”

Safer Solvents and Processes

“…197 Elsewhere the formation of polyfluorene was achieved by Janiszewska and Osteryoung. 200,201 The use of a neat ionic liquid 1-methyl-3-ethylimidazolium hydrogen dichloride [C 2 -mIm][HCl 2 ] was also investigated with regard to the reduction of phenazine. The reactions studied dealt with the reduction of aromatic ketones.…”

“…198 Actual transformation of an organic moiety was achieved electrochemically in 1-methyl-3-butylimidazolium chloroaluminate systems. 200 Most of the work in electrosynthesis has been carried out in air-and moisture-sensitive ionic liquids, those containing chloroaluminates and [HCl 2 ] -; little investigation into the electrosynthetic possibilities presented by air and moisture stable ionic liquids has been attempted. 199 Reductions of perylene and phenazine have also been achieved electrochemically in basic mixtures of aluminum trichloride and 1-methyl-3-ethylimidazolium chloride.…”