Benzyl Functionalized Ionic Liquids

As a kind of compounds with strong controllability, ionic liquids have always attracted much attention. Functionalized ionic liquids can qualitatively control various properties, and obtain target materials with excellent performance. Benzyl has a strong π-π interaction. The introduction of benzyl groups into ionic liquids can extend the conjugation between ionic liquids and enhance the π-π interaction. The π-π interaction between ionic liquids can enhance its thermal stability, mechanical strength and abundance of weak forces between ions. In the benzyl functionalized ionic liquid, the cation is 1-benzyl-3-alkylimidazole, and the anion includes Cl^-, Br^-, BF₄^-, PF₆^-, etc. However, the application of this type of ionic liquid is still relatively few, mainly using its conjugation effect in separation and purification technology.

Figure 1. Common structure of benzyl functionalized ionic liquids

Applications:

• Extraction and separation: In the fields of environment, food, biology, etc., ionic liquid-dispersed liquid-liquid microextraction is a new and environmentally friendly sample pretreatment technology that integrates sampling, extraction and enrichment. It has the advantages of short extraction time, simple operation, high enrichment multiple, and less extraction solvent used. Compared with simple organic solvents, the designability of ionic liquids provides operability for improving extraction efficiency. The strong π-π interaction between benzyl functionalized ionic liquids can significantly improve the extraction efficiency, and can achieve efficient extraction and enrichment of organophosphorus pesticides and benzene ring compounds in environmental water samples. The mechanism is that the introduction of benzyl functional groups can uniform charge distribution, reduce symmetry, and help improve the extraction efficiency of aromatic compounds.
• Lubricant: The π-π interaction between the benzyl functionalized ionic liquids gives the possibility of mutual movement between molecules, making it have excellent lubricating properties. In addition, the ionic liquid can form a physical adsorption film on the metal surface to protect the metal surface with anti-friction and anti-wear properties.

Reference

• Yunchang Fan, Xing Dong, Yun Li, Yingying Zhong, Juan Miao, Shaofeng Hua. Removal of Rhodamine B from Water by Benzyl-Functionalized Ionic Liquids [J]. Clean-soil,air,water 2016, 44, 1106-1112.