INFLUENCE OF ACETONITRILE, DIMETHYLSULFOXIDE AND LEAD ON THE ELECTROOXIDATION OF SMALL ORGANIC-MOLECULES - AN ONLINE MASS-SPECTROSCOPY STUDY

The electro-oxidation of HCOOH in 0.05 M H2SO4 was investigated in an electrolyte containing Pb2+ or acetonitrile. The catalytic effect caus ed by the simultaneous presence of lead and acetonitrile is higher tha n that of acetonitrile or lead alone. The influence of acetonitrile on the electro-oxidation of formamide and dimethylformamide at a painted Pt electrode in 0.05 M H2SO4 was also investigated. At potentials bel ow 0.6 V/RHE the oxidation of formamide is catalysed by the presence o f acetonitrile in the electrolyte; however, the electro-oxidation of d imethylformamide is inhibited under these conditions. The electro-oxid ation of HCOOH was also investigated in the presence of dimethylsulpho xide (DMSO). It was found that DMSO inhibits the oxidation of formic a cid. The addition of Pb2+ to the DMSO-containing electrolyte is able t o compensate for the inhibitory effect of DMSO. Nevertheless, the orig inal catalytic effect of lead is not obtained in the presence of DMSO. In contrast with formic acid, the electro-oxidation of methanol at a painted Pt electrode in an electrolyte containing 0.05 M H2SO4+0.1 M C H3OH is inhibited by the presence of acetonitrile. Furthermore, the in hibitory effect of the same concentration of DMSO is stronger than tha t of acetonitrile.