Electrochemical Studies of Aromatic Ketones in 1-Ethyl-3-Methylimidazolium

The electrochemical reduction of 9-fluorenone and benzophenone has been studied in the 1-ethyl-3-methylimidazolium tetrafluoroborate ( EMIBF4) ionic liquid. A comparison of potential separation for successive 9-fluorenone reduction processes in EMIBF4 at 100 mV/s with those in acetonitrile provides evidence for complexation of the 9-fluorenone dianion by the EMI+ cation. Complexation of the 9-fluorenone carbonyl oxygen by added BF3 etherate has also been studied, producing a positive potential shift for the reduction process. The reduction of benzophenone in EMIBF4 shows two successive electron transfers only at higher scan rates ( 1 V/s), suggesting that proton transfer and / or complexation of benzophenone reduction products by the EMI+ cation may be involved. The peak potential separation for the benzophenone reduction processes at 1 V/s is similar to that for 9-fluorenone at 100 mV/s, indicating that the EMI+ cation also complexes the benzophenone dianion