Ethanol splitting in bipolar membranes: Evidence from NMR analysis

Bipolar membranes were reported to split alcohol into alkoxide ions and H+; however, there is no direct evidence for ethanol splitting, i.e., the existence of ethoxide ions. This work uses ethanol for alcohol splitting test and 1H NMR for the identification of ethoxide ions. According to the spectra analysis, the chemical shifts of proton H, δ 3.736–3.666 (q, 2H) and δ 1.255–1.209 (t, 3H) can only be ascribed to CH3CH2O−. Therefore, this work first proves ethanol splitting in bipolar membranes by detecting the existence of sodium ethoxide. To further extend the application of electrodialysis to non-aqueous systems (as in organic synthesis), membranes of better solvent-resistance are needed to be developed.