Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent

T. Kavitha, Pankaj Attri, Pannuru Venkatesu, R. S.Rama Devi, T. Hofman

Research output: Contribution to journalArticlepeer-review

68 Citations (Scopus)


Mixing of ionic liquids (ILs) with molecular solvent can expand the range of structural properties and the scope of molecular interactions between the molecules of the solvents. Exploiting of these phenomena essentially require a basic fundamental understanding of mixing behavior of ILs with molecular solvents. In this context, a series of protic ILs possessing tetra-alkyl ammonium cation [R4N]+ with commonly used anion hydroxide [OH]- were synthesized and characterized by temperature dependent thermophysical properties. The ILs [R4N]+[OH]- are varying only in the length of alkyl chain (R is methyl, ethyl, propyl, or butyl) of tetra-alkyl ammonium on the cationic part. The ILs used for the present study included tetramethyl ammonium hydroxide [(CH3) 4N]+[OH]- (TMAH), tetraethyl ammonium hydroxide [(C2H5)4N]+[OH]- (TEAH), tetrapropyl ammonium hydroxide [(C3H7)4N] +[OH]- (TPAH) and tetrabutyl ammonium hydroxide [(C 4H9)4N]+[OH]- (TBAH). The alkyl chain length effect has been analyzed by precise measurements such as densities (ρ), ultrasonic sound velocity (u), and viscosity (η) of these ILs with polar solvent, N-methyl-2-pyrrolidone (NMP), over the full composition range as a function of temperature. The excess molar volume (VE), the deviation in isentropic compressibility (Δκs) and deviation in viscosity (Δη) were predicted using these properties as a function of the concentration of ILs. Redlich-Kister polynomial was used to correlate the results. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and NMP molecules. Later, the hydrogen bonding features between ILs and NMP were also analyzed using a molecular modeling program with the help of HyperChem 7.

Original languageEnglish
Pages (from-to)4561-4574
Number of pages14
JournalJournal of Physical Chemistry B
Issue number15
Publication statusPublished - Apr 19 2012
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry


Dive into the research topics of 'Influence of alkyl chain length and temperature on thermophysical properties of ammonium-based ionic liquids with molecular solvent'. Together they form a unique fingerprint.

Cite this