Electrochemical and Spectroscopic Studies of 1,4‐Benzoquinone in Ambient Temperature Chloroaluminate Ionic Liquids

Abstract

The chemical, electrochemical, and spectroscopic properties of 1,4‐benzoquinone (Q) have been studied in the aluminum chloride:1‐ethyl‐3‐methylimidazolium chloride ionic liquid. In basic melts , fast scan voltammetry (up to 1000 V s−1) shows that Q reduces to Q2− in a fast two‐electron step, probably followed by solvation of the dianion. Infrared and visible spectroscopic data, and electrochemical measurements show that Q reacts with Cl− in basic melts producing the dianion of monochlorohydroquinone. Q shows no electrochemical response in acidic melts (1.2:1 ). However, it reacts with the solvent and eventually generates which is electrochemically detected at a Pt electrode. The corresponding IR spectrum of the solution lacks the major absorption band in the vicinity of 1657 cm−1, where the C=O stretching band is observed for Q in neutral or basic melts. When the acidic melt is neutralized and made basic by the addition of , the cyclic voltammogram shows no presence of Q, which indicates that its reaction with the acidic melt is complete.