Article

Stability of Superoxide Ion in Imidazolium Cation-Based Room-Temperature Ionic Liquids

Department of Electronic Chemistry, Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Mail Box G1-5, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502, Japan.
The Journal of Physical Chemistry A (Impact Factor: 2.78). 02/2009; 113(5):912-6. DOI: 10.1021/jp807541z
Source: PubMed

ABSTRACT The stability of superoxide ion (O(2)(*-)) generated chemically by dissolving KO(2) in dried dimethyl sulfoxide solutions containing imidazolium cation [e.g., 1-ethyl-3-methylimidazolium (EMI(+)) and 1-n-butyl-2,3-dimethylimidazolium (BMMI(+))] based ionic liquids (ILs) was investigated with UV-visible spectroscopic, NMR, and voltammetric techniques and an ab initio molecular orbital calculation. UV-visible spectroscopic and cyclic voltammetric measurements reveal that the O(2)(*-) species reacts with BMMI(+) and EMI(+) cations of ILs to form hydrogen peroxide. The pseudo first order rate constant for the reaction of BMMI(+) and O(2)(*-) species was found to be about 2.5 x 10(-3) s(-1). With a molecular orbital calculation, the O(2)(*-) species is understood to attack the 2-position (C-2) of the imidazolium ring (i.e., BMMI(+)) to form an ion pair complex in which one oxygen atom is bounded to C-2 and the other to the hydrogen atom of -CH(3) group attached to C-2. Eventually, the ion pair complex of BMMI(+) cation and O(2)(*-) species undergoes a ring opening reaction as evidenced with (1)H NMR measurement.

0 Followers
 · 
203 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Increase in energy demand and consumption has been accompanied by a corresponding increase in sulfur emissions. These pollutants have both health and economic consequences. Furthermore, it significantly reduces the efficiency of advanced emission control systems of diesel engines, thereby indirectly causing more harm to the environment. This resulted in stringent sulfur emission limit down to about 15 ppm or less and in turn served as an incentive for research into alternative sulfur reduction technologies. Although feasible improvements to hydrodesulfurization are currently under investigation, adsorptive, extractive, oxidative and biodesulfurization have also been studied in recent years. Oxidative desulfurization appears to be one of the most promising desulfurization technologies due to its broadness and compatibility with other technologies such as extractive, adsorptive and biodesulfurization. The advent of ionic liquids as extraction solvents has made this even more so. This work, therefore, reviews the different approaches and investigations carried out on oxidative desulfurization while identifying research gaps and giving important recommendations.
    08/2014; 30(4). DOI:10.1515/revce-2014-0001
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanoporous ionic organic networks (PIONs) with a high ionic density (three cation-anion pairs per unit) have been synthesized by a facile SN2 nucleophilic substitution reaction. Owing to the electrostatic and steric effect, those ionic networks with porous channels can stabilize and support gold (Au) nanoparticles (NPs) in 1-2 nm. The Au@PION hybrid materials used as a heterogeneous catalyst were highly active, selective, and stable in the aerobic oxidation of saturated alcohols.
    Nano Letters 01/2015; DOI:10.1021/nl504780j · 12.94 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The use of 1-methyl-1-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr14TFSI) electrolyte in different Li-O2 cell setups is here investigated. In a one-compartment Li-O2 cell, the pyrrolidinium ion is reduced on metallic lithium, producing substantial amounts of alkenes and amines. To avoid this, a simple two-compartment cell is used, with propylene carbonate as anode electrolyte and a Li+-ion solid electrolyte as separator. Another explored option is the substitution of lithium in the one-compartment cell with lithiated LTO (LLTO). Unfortunately, the absence of an SEI leads to the reduction of O2 at LLTO, making it not useful as counter electrode for Li-O2 cell evaluation. All the configurations above are characterized by a first discharge specific capacity double than that obtained with unreactive electrolytes. The use of an edge-sealed two-compartment LLTO-Vulcan cell resulted in the usual discharge capacity of ≈200 mAh g−1C at the first cycle, eliminating the effects of Pyr14TFSI reduction; nevertheless, the poor cyclability even in this cell design suggests that Pyr14TFSI might not have sufficient long-term stability against the attack of O2•− during discharge or of oxygen species during charge.
    Journal of The Electrochemical Society 09/2014; 160(14):A1992-A2001. DOI:10.1149/2.1131412jes · 2.86 Impact Factor

Similar Publications