Investigation of the chemical generation and long term stability of superoxide ion, O2·-, in three bis (trifluoromethylsulfonyl) imide [TFSI-] anion based ionic liquids, ILs, with cations of 1-(3-methoxypropyl)-1-methylpiperidinium [MOPMPip+], 1-hexyl-1-methyl-pyrrolidinium [HMPyrr+] and trihexyl (tetradecyl) phosphonium [P14,666+] has been conducted. The chemical generation of O2·- in ILs was carried out by dissolving potassium superoxide, KO 2, in the corresponding IL, while electrochemical generation was carried out by reduction of O2 to O2·- in ILs followed by analysis using cyclic voltammetry technique. It was found the solubility of KO2 in the studied ILs depends on the structure of ILs in addition to the temperature. However, in all cases the solubility was high enough for many applications. The Long term stability of the generated O2·- was carried out by the application of KO2 in aprotic solvent, dimethyl sulfoxide, in the presence of the corresponding IL. UV-visible spectrophotometry at an absorbance range of 190-400 nm was used to determine the stability of O2·-. It was found that ILs containing [MOPMPip+] and [HMPyrr+] cations offer a promising long term stability of O2·- for various reactions and applications, while consumption of O2·- in [P14,666+][TFSI-] with a rate constant of 16.2 × 10-5 s-1 indicates that the generated O2·- in this IL is not stable enough for practical applications. To our best knowledge this is the first time a piperidinium and pyrrolidinium based ILs were used as media for the chemical generation of O2·-. The chemically generated O2·- by dissolving KO2 was then used for the destruction of chlorobenzenes in [MOPMPip+][TFSI-] and [HMPyrr+][TFSI-] at ambient conditions. This work presents the first attempt to use KO2 for the destruction of chlorinated aromatic hydrocarbons in ILs media.
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