Piperidinium-Based Ionic Liquids

Ionic liquid refers to a substance that is liquid at or near room temperature and consists only of ions. Many types of ionic liquids, ionic liquid precursor of different organic cation, can be divided into ionic liquid imidazole salts, pyridine salts, quaternary ammonium salts and quaternary phosphonium salts and the like; According to the solubility of ionic liquids in water, ionic liquids can also be divided into hydrophilic ionic liquids and hydrophobic ionic liquids. Among many ionic liquids, the proportion of ionic liquids with piperidine as the main functional group is relatively small. It can be modified by introducing R groups with different chemical structures to obtain functionalized ionic liquids. Functionalized ionic liquids can be widely used in fine organic synthesis, catalysis, electrochemistry, materials science, energy and other fields. Piperidine functionalized ionic liquids can be used in surfactants, catalyzing organic reactions and other fields.

Figure 1. Common composition of piperidinium-based ionic liquids

Applications:

• Surfactant: Piperidinium-based ionic liquid surfactant is a cationic functional surfactant. The hydrophobic side chain and the hydrophilic group have amphiphilic properties, and the polarity and hydrophilicity/lipophilicity can be adjusted by adjusting the length of the side chain and selecting an appropriate anion. It can be applied to the fields of microemulsion, material preparation, analysis, etc., and has broad application prospects.
• Catalytic fuel desulfurization: As a petroleum refining product, diesel fuel contains a large amount of environmental pollutants SO_x, NO_x, CO, etc. in the exhaust gas from combustion. Among them, SO_x is increasingly harmful to the environment. Piperidinium-based ionic liquids can catalyze and oxidize fuel desulfurization. After the reaction is completed, the upper oil phase is separated to obtain desulfurized oil products for oil processing.
• Modification of electrode materials: Piperidine ionic liquids as modifiers can modify traditional electrode materials to significantly enhance their electrochemical responsivity, improve the reversibility of electrode reactions, effectively improve interface conductivity, reduce interface resistance, and accelerate electron transfer rate, and increase the peak current response.

Reference

• Ramesh L. Gardas, Henrique F. Costa, Mara G. Freire, Pedro J. Carvalho, Isabel M. Marrucho, Isabel M. A. Fonseca, Abel G. M. Ferreira, João A. P. Coutinho. Densities and Derived Thermodynamic Properties of Imidazolium-, Pyridinium-, Pyrrolidinium-, and Piperidinium-Based Ionic Liquids[J]. Chem. Eng. Data 2008, 53, 3, 805–811.