Water as an in Situ NMR Indicator for Impurity Acids in Ionic Liquids

Yoshiro Yasaka, Chihiro Wakai, Nobuyuki Matubayasi, Masaru Nakahara

Anal Chem. 2009 Jan 1;81(1):400-7.

PMID: 19117465

Abstract:

A sensitive in situ NMR spectroscopic method for detecting acids contaminating ionic liquids (ILs) has been developed. The chemical shift and the spectral width of water added to ILs were used as indicators to measure the impurity acid level. Owing to the high resolution power of NMR, the detection limit is below the level of 10(-3) mol kg(-1). A new method is applicable to a number of commonly used ILs such as the imidazolium- and ammonium-based ILs except for those composed of acidic cations or anions. The method was utilized to monitor the purification efficiency in the recrystallization of a typical hydrophilic IL, 1-butyl-3-methylimidazolium methanesulfonate from acetone. It was demonstrated that impurity acids can be almost perfectly removed by single or double recrystallization.

Chemicals Related in the Paper:

Catalog Number	Product Name	Structure	CAS Number	Price
AP342789815	1-Butyl-3-methylimidazolium methanesulfonate		342789-81-5	Price