Water as an in situ NMR indicator for impurity acids in ionic liquids

Analytical Chemistry

Volumn 81, Issue 1, 2009, Pages 400-407

  Yasaka, Yoshiro ^a   Wakai, Chihiro ^a   Matubayasi, Nobuyuki ^a   Nakahara, Masaru ^a  

^a KYOTO UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

ACIDIC CATIONS; DETECTION LIMITS; HIGH RESOLUTIONS; IMIDAZOLIUM; IN-SITU; METHANESULFONATE; PURIFICATION EFFICIENCIES; RECRYSTALLIZATION; SPECTRAL WIDTHS; SPECTROSCOPIC METHODS;

ACETONE; ACIDS; AMMONIUM COMPOUNDS; INDICATORS (CHEMICAL); IONIZATION OF LIQUIDS; IONS; LIQUIDS; NUCLEAR MAGNETIC RESONANCE; NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY; RECRYSTALLIZATION (METALLURGY);

IONIC LIQUIDS;

EID: 58149457794     PISSN: 00032700     EISSN: None     Source Type: Journal    
DOI: 10.1021/ac801767u     Document Type: Article

References (23)

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15. +, they are not individually treated here since we are involved in semiquantitative analysis.
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20. The integral of the exchangeable proton peak was measured at a higher temperature of 100°C to avoid the overlapping with the proton peaks of the solvent IL; the exchangeable proton peak shifts upfield (the decrease of the chemical shift) as the temperature is raised.
21. As reported previously in ref 7, polar solutes in ILs are strongly attracted by the component anions through Coulombic interactions. The dynamics of such solutes significantly slows down, and the corresponding NMR signal broadens.
22. This relation becomes invalid when the concentration of HA increases too much because the proton exchange crosses over from the slow exchange regime into the intermediate regime or even into the fast exchange regime; see Figure 8.
23. a values are available only in room temperature water for comparison. However, it is not expected that differences in the proton exchange rate of weak acids in ILs strictly follow their acid strength sequence in water.