Electrochemistry of chloride in ambient room temperature ionic liquids: Formation of oxychloride species

The electrochemistry of chloride in water-containing hydrophobic ([Emim][NTf2] and [BmPyrr][NTf2]) and hydrophilic ([Emim][OAc]) ionic liquids (ILs) has been described in detail for the first time. Cyclic voltammetric studies at a glassy carbon electrode note the significant effect of ambient water on the electrochemistry of chloride, with different outcomes based upon the hydrophilicity (c.f. water content) of the hygroscopic ILs. Added hydroxide highlighted this as a reactive species. Evaluation of chloride, hypochlorite, chlorite, chlorate and perchlorate electrochemistry (chlorine oxidation states -1, +1, +3, +5 and +7) was performed. Ultimately, the electrochemically formed chlorine (Cl-2) was determined to react with water or hydroxide to yield higher oxidation state species via oxychloride intermediates (e.g. hypochlorite) through multiple EC steps, likely resulting in chlorate as the final product. (C) 2013 Elsevier B.V. All rights reserved.