The Preparation, Properties Of Compound Ionic Liquid And Its Application In Electric Reduction Of Nitrobenzene

The production of amine azo and aminophenol aromatic compounds by reducing nitrocompounds is important organic synthesis reaction, which has high economic and social value. Ionic liquids taking the place of traditional solvent and electrolyte in electrochemical reduction of nitrocompounds has green characteristics of simple composition, easy separation and media recycle. It is important for researches and applications of functionalized ionic liquids to improve the electroreduction property of nitrocompounds. Binary composite ionic liquids by different volume ratio of hydrophilic ionic liquids1-Butyl-3-methylimidazolium tetrafluoroborate (BMimBF4) and hydrophobic ionic liquids1-Butyl-3-methylimidazolium hexafluorophosphate (BMimPF6) in accordance with their different properties are synthesized in the study. It can be complemented and improved each other in the nature of the properties of functionalized ionic liquids in a simple and inexpensive way, which can be used to the study of electroreduction of nitrobenzene.Composite ionic liquids of BMimBF4and BMimPF6(volume ratio of4:1,3:1,2:1,1:1,1:2,1:3,1:4) are prepared. The interactions between binary composite ionic liquids, among ternary mixture system with water or nitrobenzene, electrochemical window, kinematic viscosity and electroconductibility, and the change regularity of different system are determined. Explore electrochemical and kinetic behavior of nitrobenzene in composite ionic liquid and composite ionic liquid-H2O by different electrochemical measuring technology (cyclic voltammetry CV, electrochemical impedance spectroscopy EIS, steady-state polarization curves I/E, chronocoulometry Q-t, chronoampermetry I-t). The nitrobenzene is reducted selectively by different electrolytic technologies (potentiostatic electrolysis and constant current electrolysis).The results indicated that the absorption peaks of ultraviolet spectrophotometry (UV) of nitrobenzene, aniline and azobenzene in different composite ionic liquids are similar to pure ionic liquid. The absorption intensity changes with the concentration of nitrobenzene, aniline and azobenzene in composite ionic liquid. The electrochemical window of different composite ionic liquids has an irregular change, which improves the shortcoming of electrochemical window of BMimBF4. Kinematic viscosity and electroconductibility of different composite ionic liquids has a regular change, and this change remains when adding in water and nitrobenzene. The kinetic property of composite ionic liquids can be controlled easily due to that change.The electroreduction characteristics of nitrobenzene on Pt and Cu in composite ionic liquids (3:1and4:1) are improved remarkably in comparison with pure ionic liquid, which is similar to composite ionic liquids-H2O. The main influence factors of the electrochemical reduction of nitrobenzene in4:1composite ionic liquids are scan rate, scan cycle, temperature, concentration of nitrobenzene, concentration of water and electrode material. With increasing the scan rate, cyclic voltammetry has a regular change, the first peak potential has no change and the second peak potential is shifted to the negative direction and the responding peak current is increasing. The reaction velocity of nitrobenzene in composite ionic liquid on Pt is controlled by diffusion. With increasing temperature, the peak current is increased, and the first peak potential is shifted to the negative direction slightly and the second peak potential has no change. With increasing the concentration of nitrobenzene, the peak current is increased and the peak potential is shifted to the negative direction slightly, correspondingly. Reduction peak is coming up and responding current is decreased when scan cycle rising, and the decrease is slow gradually. With increasing water to composite ionic liquid, the first and second peak potential is shifted to the positive direction and the responding peak current is increasing. Pt and Cu have more superior selectivity in electroreduction of nitrobenzene in different electrode material. With increasing temperature, transfer coefficient and diffusion coefficient of nitrobenzene in different ionic liquid/electrode system is increasing. The main product is aniline and azobenzene under different conditions of electrolysis.