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Keywords:

  • Ionic liquids;
  • Zwitterions;
  • Imidazolium;
  • X-ray diffraction;
  • Synthesis

Abstract

The reaction of 1-alkylimidazoles (alkyl = methyl, ethyl, propyl, 2-cyanoethyl) with 1,4-butane sultone in equimolar stoichiometry resulted in the formation of 4-(1-methylimidazolium)butane-1-sulfonate SBMIm, 4-(1-ethylimidazolium)butane-1-sulfonate SBEIm, 4-(1-propylimidazolium)butane-1-sulfonate SBPIm, and 4-(1-(2-cyanoethyl)imidazolium)butane-1-sulfonate SBCNEtIm, respectively, in high yields. Properties of these four imidazolium-based zwitterionic compounds were investigated with respect to question of their use as suitable precursors for Ionic Liquids. The structures of the compounds SBMIm, SBEIm, and SBPIm were determined by single-crystal X-ray diffraction. SBMIm and SBEIm crystallize both in the triclinic space group Pequation image, SBMIm: a = 8.4454(6), b = 8.4492(6), c = 8.7532(7) Å, α = 66.610(2), β = 66.235(2), γ = 70.625(2)°, Z = 2, R1(F)/wR2(F2) = 0.0279/0.0832; SBEIm: a = 8.4359(2), b = 8.5900(2), c = 8.6790(2) Å, α = 73.487(2), β = 71.228(1), γ = 70.979(2)°, Z = 2, R1(F)/wR2(F2) = 0.0333/0.0820; SBPIm with monoclinic symmetry, space group P21/c: Z = 4; a = 7.2979(3), b = 17.5312(8), c = 9.5682(4) Å, β = 90.922(3)°, R1(F)/wR2(F2) = 0.0507/0.1198.