Heat of mixing profile, complexation curve and spectroscopic investigation of binary mixtures containing bicyclic Brønsted superbase DBN with hydrogen ethanoate

Gordon W. Driver*, Lisette J.M. Sprakel, Ilkka Kilpeläinen, Boelo Schuur

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Isothermal titration calorimetry (ITC) experiments were performed for investigation of binary mixtures comprised of the Brønsted superbase DBN with hydrogen ethanoate (AcOH). The heat of mixing (HE) profile was recorded at (343.15 ± 0.1) K and fitted with a 5-parameter Redlich-Kister (RK) polynomial. RK fit parameters were subsequently used to quantify partial molar heats of mixing, xiHiE, for each component i. ITC-based complexometric titration data for the binary mixtures were recorded separately in methyl isobutyl ketone (mibk) and dodecane, to investigate the energetics of non-random clustering phenomena. Variable temperature 1H-NMR in combination with ATR-FTIR spectroscopic analyses were employed in parallel for elucidation and verification of liquid state ion speciation. These investigations reveal a strongly non-ideal system, and indicate “superbase” character of DBN is preserved for specific compositions where stoichiometric ionic liquids (ILs) form. Available ion speciation has been found to include [DBN-H]+, [AcO] as well as μ2-hydrogen-bridged, hydrogen-bonded homoassociate anions, of the type [H(OAc)2], with double liquid salt formation characterising various compositions based on spectroscopic determinations.

Original languageEnglish
Article number106516
Number of pages9
JournalJournal of chemical thermodynamics
Volume161
Early online date8 May 2021
DOIs
Publication statusPublished - Oct 2021

Keywords

  • Complexometric titration
  • Double liquid salt
  • Heat of mixing
  • Ionic liquids
  • Isothermal titration calorimetry
  • Superbase

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