Kiss László
Department of Organic and Medicinal Chemistry, Faculty of Pharmacy, University of Pécs, Honvéd Street 1, H-7624 Pécs, Hungary.
János Szentágothai Research Center, University of Pécs, Ifjúság Street 20, H-7624 Pécs, Hungary.
Methods Protoc. 2024 Dec 20;7(6):102. doi: 10.3390/mps7060102.
An electrochemical investigation of 1,2- and 1,4-dihydroxybenzenes was carried out with platinum macro- and microelectrodes using square wave and cyclic voltammetry techniques. Furthermore, the effect of the two solvents-acetic acid and ethyl acetate-was compared. When using square wave voltammetry, signals only appeared at lower frequencies and only when the supporting electrolyte was in excess, as expected due to the relatively low permittivity of the used solvents. The behavior of hydroquinone and catechol did not differ significantly from that of their derivatives (dihydroxybenzaldehydes, dihydroxybenzoic acids and 2',5'-dihydroxyacetophenone). When the cyclic voltammetric experiments using a microelectrode were extended to higher anodic potentials, electrode fouling was very significant in ethyl acetate after the potential region where steady-state oxidation to the corresponding quinone occurs. The substituent effect was not significant here either, which was proven by using different functional groups in different positions. In contrast, the position had a dramatic influence on the susceptibility to electropolymerization, as 1,2-dihydroxybenzenes-independent of the nature of the substituent on the benzene ring-deactivated the electrode, while 1,4-dihydroxybenzenes did not, possibly due to the different solubilities of the polymers formed from the primary oxidation product (quinones). A user-friendly analytical procedure is also proposed that uses an electropolymerization reaction and does not require frequent cleaning of the electrode via polishing, which is required usually especially with a microelectrode.
采用方波伏安法和循环伏安法技术，使用铂宏观电极和微电极对1,2 - 二羟基苯和1,4 - 二羟基苯进行了电化学研究。此外，还比较了乙酸和乙酸乙酯这两种溶剂的影响。使用方波伏安法时，信号仅在较低频率下出现，且仅在支持电解质过量时出现，这是由于所用溶剂的相对低介电常数所致。对苯二酚和邻苯二酚与其衍生物（二羟基苯甲醛、二羟基苯甲酸和2',5'-二羟基苯乙酮）的行为没有显著差异。当使用微电极进行的循环伏安实验扩展到更高的阳极电位时，在乙酸乙酯中，在发生向相应醌的稳态氧化的电位区域之后，电极污染非常显著。在此处取代基效应也不显著，这通过在不同位置使用不同官能团得到了证明。相比之下，位置对电聚合敏感性有显著影响，因为1,2 - 二羟基苯 - 与苯环上取代基的性质无关 - 使电极失活，而1,4 - 二羟基苯则不会，这可能是由于由初级氧化产物（醌）形成的聚合物的不同溶解度所致。还提出了一种用户友好的分析程序，该程序使用电聚合反应，并且不需要像通常特别是对于微电极那样频繁地通过抛光来清洁电极。
