硝基苯与离子液体的相互作用对硝基苯电还原传递系数的影响

应用紫外光谱研究了离子液体和硝基苯的相互作用, 硝基苯的紫外光谱受离子液体的影响, 硝基的吸收峰红移, 末端吸收消失. 用循环伏安法研究硝基苯电还原过程中第2个电子转移的传递系数(α)随外界条件变化所呈现复杂的变化规律. 硝基苯和水的介电性质、硝基苯和水与离子液体的相互作用对α产生复杂影响. 硝基苯浓度增加使α减小, 离子液体的咪唑侧链增长也使α减小. 相同硝基苯浓度时, 水的浓度较低时, α随水的浓度增加变小; 水的浓度较高时, α随水的浓度增加稍微变大. 温度升高α值增大.

Effect of the Interaction between Nitrobenzene and Ionic Liquids on the Transfer Coefficient of the Nitrobenzene Electrochemical Reduction

The interaction between ionic liquids (ILs) and nitrobenzene was investigated using ultraviolet spectroscopy. Compared to the ultraviolet spectrum in cyclohexane and water, a red shift of the absorption peak of the nitro group was observed in ionic liquids and no end absorption was found when the wavelength was less than 210 nm. These phenomena may be attributed to the strong interaction between ILs and nitrobenzene. The transfer coefficient (α) of the electrochemical reduction of nitrobenzene for transferring the second electron in RMimBF4 (1-alkyl-3-methylimidazolium tetrafluoroborate) was investigated by cyclic voltammetry. The effect of the dielectric nature of nitrobenzene and water on the dielectric constants of the solution and on the capacitance of the electric double layer as well as the interaction between EMimBF4 (1-ethyl-3-methylimidazolium tetrafluoroborate) and nitrobenzene and water was found to have a complicated effect on α. Increasing the concentration of nitrobenzene during the electrochemical reduction in RMimBF4, α decreased. Increasing the temperature the value of α increased while increasing the length of the imidazolium side chain had an opposite effect. At the same nitrobenzene concentration, with an increase in the water concentration α was reduced in EMimBF4-H2O system at lower water concentration and had reverse effect at higher water concentration.