Abstract: Abstract Rare earths metal complexes and caprolactam-cation-based Bronsted acid ionic liquids (ILs) were prepared and used as solvent and catalyst in the nitration of toluene and 1 equiv of 67% nitric acid. The structure of the ionic liquid was characterized by 1H NMR. The effects of reaction temperature, reaction time and the type and amount of catalyst on product yield and para-selectivity for the nitration of toluene were investigated. Nitrotoluene with the yield of 46.5% and ortho-para isomer ration 1.1 was obtained under the optimal conditions. In addition, the mixture of IL and rare earths metal complex could be removed easily and recycled 4 times with a little decreasing yield and the same para-selectivity, which opens up possibility of a more economic and green process.

Key words: Toluene, Ionic liquid, Rare earths metal, Nitration