Efficient catalytic reduction of azo dyes by N,N-dimethylformamide mediated by viologen

Abstract

A novel and efficient electron-transfer method has been developed for the reduction of azo dyes using viologen as an electron transfer catalyst in the mixed solvent composed of N,N-dimethylformamide (DMF) and H₂O. In this reaction, DMF is not only used as a solvent for the reaction but also works as an active reducing agent under refluxing conditions. Viologen, as the electron transfer catalyst plays an important role in mediating DMF reduction of azo dyes. The reaction does not take place in the absence of either DMF or viologen. The synergistic effect of viologen and DMF makes azo dye reduction very fast and efficient. The novel method could be used for decoloration of azo dyes in wastewater and organic synthesis.