邻溴苯甲酸电化学脱溴反应的原位红外光谱研究

In situ FTIR Studies on Electrochemical Debromination Reaction of 2-Bromobenzoic Acid

采用循环伏安法研究了水溶液中邻溴苯甲酸在不同电极上的电化学还原脱溴反应,与Ti和C电极相比,Cu电极对邻溴苯甲酸有较好的电化学还原活性.采用电化学原位红外反射光谱分析了反应机理,结果表明,邻溴苯甲酸在Cu电极上的电还原脱溴反应是一个脱溴加氢的过程,邻溴苯甲酸在电极表面首先得到一个电子变成邻溴苯甲酸自由基负离子,然后脱去溴离子得到苯甲酸自由基,该自由基再得到一个电子变成苯甲酸负离子;最后加成氢质子得到最终产物苯甲酸,产物通过恒电流电解实验得到了进一步证实.

The electrocatalytic reductive debromination has been extensively investigated as a technology for the detoxification and disposal of organic halides in industrial effluents.Cyclic voltammetry and in situ FTIR were employed to study the electrochemical hydrodebromination mechanism of 2-bromobenzoic acid in alkaline solution.The electrocatalytic reductive debromination of 2-bromobenzoic acid in aqueous solution on titanium,graphite and copper electrode was investigated by cyclic voltammogram.Compared with titanium and graphite electrodes,copper electrode exhibited a high electrocatalytic activity for the reductive reaction of 2-bromobenzoic acid.In situ FTIR result suggested that the mechanism of the reaction was electrochemical hydrodebromination process.2-Bromobenzoic acid was electroreduced to its free radical ion after receiving an electron firstly.Then the free radical ion was further debrominated to produce benzoic acid free radical at more negative potential.After receiving another electron and proton,benzoic acid was obtained,which had been confirmed by constant current electrolysis experiments.