Anodic thiocyanation of mono- and disubstituted aromatic compounds

The in situ and environmentally friendly thiocyanation (no use of toxic oxidizing agents) electrochemical thiocyanation of aromatic compounds involving various derivatives of anisole and aniline to afford aromatic thiocyanates have been studied in organic acidic media. The initial electrochemical step involves anodic oxidation of thiocyanate anion to its radical (SCN), followed by dimerization to thiocyanogen (SCN)₂. The latter is polarized by the acidic solvent and attacks the aromatic nucleus of the substrate to afford the corresponding thiocyanate derivative. The sole thiocyanate products obtained in each case shows high regio-selectivity (no ortho isomer was observed) for the monosubstituted aromatics and high isomer-selectivity (no isothiocyanate isomer was detected) for both mono- and disubstituted aromatics.