Review—Use of 1,1,1,3,3,3–hexafluoro–2–propanol (HFIP) Co-Solvent Mixtures in Organic Electrosynthesis

Abstract

Because of the necessity of carry out electrolysis reactions with considerable quantity of organic molecules, the balance between solubility of starting material, solution conductivity and electrochemical stability of medium and intermediates are key factors in organic electrosynthesis. HFIP has several properties that favor its use in this research area as solvent, among them, its high hydrogen-bond donor has opened the possibility of fine tuning reactivity, mainly in anodic reactions because of the helpful effect on the stability of positive intermediates. The cost of this solvent has limited its broad application in chemistry, including electrosynthesis, but the possibility of using mixtures with other cosolvents has demonstrated to help to expand its use without losing the beneficial effect on the intermediates. In recent years several HFIP mixtures (HFIP/MeOH, HFIP/CH2Cl2, HFIP/H2O, HFIP/ACN, HFIP/MeNO2) have permitted the control the chemical microstructure of the electrolysis media and have let to adjust the solvent properties to fulfill the necessity of electrosynthesis. In this review will be discussed the general properties of HFIP and the mixtures reported to carry out electrochemical synthetic transformations of organic molecules, as well as the reactions where has been demonstrated the beneficial effect of HFIP solvent mixtures in the control of the electrogenerated intermediates. This approach has succeeded in organic electrosynthesis.