质子惰性介质中o,m,p-硝基甲苯在铂微盘电极上的电化学行为

Electrochemical behavior of ortho-,meta-,and para-nitrotoluene in aprotic medium on Pt micro-disk electrode

在298 K下,以铂微盘电极为工作电极,在含有0.1 mol/L四丁基高氯酸铵(TBAP)为支持电解质的N,N-二甲基甲酰胺(DMF)有机溶液中分别测定了0.01 mol/L邻-硝基甲苯、间-硝基甲苯和对-硝基甲苯的循环伏安曲线,讨论了扫描速度对硝基甲苯电化学行为的影响,根据实验结果推测硝基甲苯还原反应是转移电子数为1的受扩散控制的可逆过程.并对不同位甲基取代硝基甲苯的电还原行为进行了比较,结果表明在质子惰性介质中,间硝基甲苯最容易被还原,对硝基甲苯次之,而邻硝基甲苯最难被还原.

Electrochemical reduction of ortho-, meta-, and para-nitrotoluene in aprotie medium on Pt micro-disk electrode has been investigated using cyclic voltammetry. The effect of scan rate on electrochemical characteristics of nitrotoluene was discussed. The electrochemical reduction of nitro compounds showed a reversible cathodic wave corresponding to one electron transfer, and formed the nitro radical anion, which was controlled by diffusion. Also, a comparison among ortho-, recta- and para-nitrotoluene relating the effects of different positions of methyl on nitrobenzene on the easiness of formation of radical in aprotie medium was presented. The reduction potential of the nitrotoluenes was. m-nitrotoluene〉 p-nitrotoluene〉 o-nitrotoluene, a plausible explanation for these results could be ascribed to the more electron-donating properties of the methyl group on the electron density of the nitro moiety in the ortho-position and para-position compared than the recta-position. And o-nitrotoluene appeared more negative than p-nitrotoluene, probably, this result could be explained on the basis that in the ortho position the nitro group suffers steric hindrance by the proximity of the methyl group provoking a little loss of eoplanarity between the nitro group and the aromatic ring.