2-[(8-Hydroxyquinoline-5-yl)azo]benzo[c]cinnoline (HQAB) was prepared and characterized by elemental analysis, MS, FTIR and 1H NMR techniques. The electrochemical reduction of HQAB has been investigated by cyclic voltammetry, chronoamperometry and controlled potential electrolysis at mercury pool electrode in the pH range 3.5–9.4. The number of electrons transferred in the electrode reaction, diffusion coefficients and standart rate constants were calculated. In acidic medium, cyclic voltammograms display four cathodic peaks, with the total exchange of 6 e– and 6 H+. By contrast, the reverse scan displays two anodic peaks. Constant potential electrolysis at –1.0 V and TLC analysis of the product reveals that the reduction of azo group (in the bridge) in HQAB does not stop at the hydrazo stage but goes further through the cleavage of –NH–NH– linkage to give amino compounds as the final products. The voltammograms recorded in basic medium exhibit two cathodic peaks corresponding to 4 e–, 4 H+ and two reverse anodic peaks, and thus the reduction stopped at hydrazo stage. A tentative mechanism for the reduction has been suggested.
2-[(8-羟基喹啉-5-基)偶氮基]苯并[c]茜芦啉(HQAB)通过元素分析、质谱、傅里叶红外和1H核磁共振技术进行了制备和表征。在pH值为3.5-9.4的汞池电极上,通过循环伏安法、计时安培法和控制电位电解法研究了HQAB的电化学还原。计算了电极反应中转移的电子数、扩散系数和标准速率常数。在酸性介质中,循环伏安图显示出四个阴极峰,总共交换了6个电子和6个H+。相反,反向扫描显示出两个阳极峰。在-1.0 V的恒定电位电解和产物的薄层色谱分析中,表明HQAB中偶氮基(在桥上)的还原不止于双氮化阶段,而是通过断裂-NH-NH-连接进一步进行,最终产生氨基化合物。在碱性介质中记录的伏安图显示出两个阴极峰和两个反向阳极峰,对应于4个电子和4个H+,因此还原停止于双氮化阶段。提出了还原机理的初步假设。