The electrodimerization mechanism of 2,4,6-trichloro- and tribromoanilines in unbuffered acetonitrile

A detailed investigation of the electro-oxidation of halogeno-substituted-anilines in aprotic solvents (DMF, MeCN) has been the subject of our recently published papers. The main aim of these investigations was to confirm the validity and details of the head to tail coupling mechanism in aqueous solution described first by Bacon and Adams [J. Am. Chem. Soc. 90 (1968) 6596]. At the same time, by using advanced electrochemical and structural chemical methods, a deeper insight could be achieved into the details of the mechanistic and thermodynamic aspects of these types of electrodimerization reactions. The problems seemed to be almost resolved when potentiometric titrations of the tri-halogenoanilines in MeCN solvent showed that the amino groups of these two compounds are not basic at all and therefore their dimerization behavior may deviate from that of other similar compounds published previously. Two main lines were followed in this investigation: (a) By using controlled potential coulometric electrolysis enough final product(s) were prepared, which were identified by separation of the product(s) on an HPLC column, coupled directly to MS. (b) Slow and fast CV of the two compounds, the application of digital simulation to the mechanism of the electrodimerization reaction, (e-p-RRC-p) and kinetic and thermodynamic parameters were determined in the case of these two tri-halogenoanilines.