Synthesis and Characterisations of Aliquat 336® and Cetylpyridinium Ionic Liquids Incorporated with Sulfonate-Based Anions

A novel series of ionic liquids based on the tricaprylmethylammonium cation [C25H54N+], in Aliquat 336 (R) and cetylpyridinium cation [C21H38N+] in cetylpyridinium chloride incorporating sulfonate-based anions were elegantly prepared by means of ion exchange between the Cl- cation with two different anions, namely, dioctylsulfosuccinate [DOSS-] and dihexylsulfosuccinate [HOSS-]. These ionic liquids were characterised using FTIR-ATR and NMR in order to identify the molecular structures of these compounds. The physical properties of these compounds, namely refractive index and thermal properties were measured at room temperature and are reported herein. ILs incorporating cetylpyridinium cations show higher thermal stability and refractive index values as compared to Aliquat ILs due to the effects of the aromatic ring on the cetylpyridinium cation as well as the longer alkyl chain on the anion of DOSS.