Electroreduction behavior of coumarin in an ionic liquid (BMIMBF₄)

The electrochemical reduction of coumarin at GC electrode in 1-n-butyl-3-methylimidazolium tetrafluoroborate(BMIMBF₄) room temperature ionic liquid is reported. Coumarin exhibits a one-electron, irreversible reduction to caroanion radical, and the latter species undergoes fast dimerization to dihydrodimer. The influences of scan rate, concentration and temperature were studied by cyclic voltammetry. The results show that the reaction is diffusion controlled. The diffusion coefficient D of coumarin in BMIMBF₄ from Chronocoulometry is 5.066 x 10^-7 cm²/s. Furthermore, the influences of water and substituting group during the electroreduction are discussed. These preliminary electrochemical experiments show encouraging results for the use of ionic liquids in a green electrochemistry.