Collect. Czech. Chem. Commun. 1999, 64, 1937-1952

Voltammetric Study of N-Benzoylthiourea and Its N',N'-Disubstituted Derivatives as Possible Electrode Modifiers

Karl-Heinz Lubert*, Lothar Beyer and Markus Guttmann

University of Leipzig, Institute of Inorganic Chemistry, Johannisallee 29, D-04103 Leipzig, Germany


The voltammetric behavior of N-benzoylthiourea (BTU) and some of its N',N'-disubstituted derivatives is studied using glassy carbon and carbon paste electrodes in ethanolic solution. Irreversible reduction of the compounds takes place in a potential range between -0.5 and -1.1 V, where carbon surface groups are reduced as well. The products formed by reductive cleavage of the C-N bond of the amide group are oxidized in the subsequent positive scan at +0.5 V. Irreversible oxidation of the thiocarbonyl group of BTU (or its derivatives) takes place at about +1.0 V followed further by an oxidation of its N',N'-dialkyl and morpholine derivatives at more positive potentials. Oxidation current at +0.8 V is only observed in the case of the N',N'-diphenyl derivative. The oxidation current at +1.0 V depends linearly on the concentration of BTU (or its derivatives) and is suitable for their electroanalytical determination with carbon electrodes. The experimental results are compared with electrochemical behavior of related compounds. Furthermore, the influence of carbon surface states is discussed. It was concluded that N',N'-disubstituted derivatives of the BTU can be employed as modifying agents for carbon electrodes applicable in the potential range from +0.7 to -0.5 V.

Keywords: Carbon paste electrode; Glassy carbon electrode; Chemical modification; Redox behavior; Thiourea derivatives; Cyclic voltammetry; Electrochemistry; Thioureas; Reductions.