Patent ID: 7119937

Claim:
A method for preparing ionic liquid precursor substantially free of colored impurities, comprising: (a) generating ionic liquid precursor for an ionic liquid that is liquid at room temperature and comprises at least one cation selected from the group consisting of lithium cation and quaternary ammonium cations, and at least one anion selected from the group consisting of trifluoromethylsulfonate (CF 3 SO 3 − ), bis(trifluoromethylsulfonyl)imide ((CF 3 SO 2 ) 2 N − ), bis(perfluoroethylsulfonyl)imide ((CF 3 CF 2 SO 2 ) 2 N − ), and tris(trifluoromethylsulfonyl)methide ((CF 3 SO 2 ) 3 C − ), the ionic liquid precursor comprising colored impurities; and (b) exposing the ionic liquid precursor to decolorizing agent, thereby removing the colored impurities.