High Viscosity of Imidazolium Ionic Liquids with the Hydrogen Sulfate Anion: A Raman Spectroscopy Study
Contribuinte(s) |
UNIVERSIDADE DE SÃO PAULO |
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Data(s) |
04/11/2013
04/11/2013
2012
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Resumo |
Ionic liquids based on 1-alkyl-3-methylimidazolium cations and the hydrogen sulfate (or bisulfate) anion, HSO4-, are much more viscous than ionic liquids with alkyl sulfates, RSO4-. The structural origin of the high viscosity of HSO4- ionic liquids is unraveled from detailed comparison of the anion Raman bands in 1-ethyl-3-methylimidazolium hydrogen sulfate and 1-butyl-3-methylimidazolium hydrogen sulfate with available data for simple HSO(4)(-) salts in crystalline phase, molten phase, and aqueous solution. Two Raman bands at 1046 and 1010 cm(-1) have been assigned as symmetric stretching modes nu(s)(S = O) of HSO4-, the latter being characteristic of chains of hydrogen-bonded anions. The intensity of this component increases in the supercooled liquid phase. For comparison purposes, Raman spectra of 1-ethyl-3-methylimidazolium ethyl sulfate and 1-butyl-3-methylimidazolium methyl sulfate have been also obtained. There is no indication of difference in the strength of hydrogen bond interactions of imidazolium cations with HSO4- or RSO4- anions. Raman spectra at high pressures, up to 2.6 GPa, are also discussed. Raman spectroscopy provides evidence that hydrogen-bonded anions resulting in anion-anion interaction is the reason for the high viscosity of imidazolium ionic liquids with HSO4-. If the ionic liquid is exposed to moisture, these structures are disrupted upon absorption of water from the atmosphere. FAPESP FAPESP CNPq CNPq |
Identificador |
JOURNAL OF PHYSICAL CHEMISTRY B, WASHINGTON, v. 116, n. 24, pp. 7281-7290, 44348, 2012 1520-6106 http://www.producao.usp.br/handle/BDPI/37771 10.1021/jp302091d1 |
Idioma(s) |
eng |
Publicador |
AMER CHEMICAL SOC WASHINGTON |
Relação |
JOURNAL OF PHYSICAL CHEMISTRY B |
Direitos |
closedAccess Copyright AMER CHEMICAL SOC |
Palavras-Chave | #CH STRETCHING VIBRATIONS #CONFORMATIONAL ISOMERISM #FERMI RESONANCE #THERMOPHYSICAL PROPERTIES #PHASE-TRANSITIONS #TEMPERATURE-RANGE #METHYL-SULFATE #HIGH-PRESSURE #AB-INITIO #BISULFATE #CHEMISTRY, PHYSICAL |
Tipo |
article original article publishedVersion |