Fundamental Principles of Organic Electrochemistry: Fundamental Aspects of Electrochemistry Dealing with Organic Molecules - Fundamentals and Applications of Organic Electrochemistry - page 10

often used as a solvent for voltammetry, many
organic substrates are water-insoluble or only
sparingly soluble. In addition, the oxygen and
hydrogen evolution reactions limit the potential
window when water is used as a solvent for
voltammetry. The voltammetric experiments
for organic substrates are therefore usually
carried out in polar organic solvents in which
the supporting electrolyte can dissociate into
ions. Acetonitrile (dielectric constant = 38) is
one of the most frequently used solvents since
its high upper and lower potential limits allow it
to be used as a solvent for both electrochemical
oxidation and reduction reactions. Other
frequently used solvents for electrochemical
oxidation are dichloromethane ( = 9),
nitromethane ( = 37), propylene carbonate (
= 64) and 1,2-dimethoxyethane ( = 3), while
other frequently used solvents for
electrochemical reduction are
N , N -dimethylformamide(DMF, = 37),
dimethylsulfoxide (DMSO, = 47),
tetrahydrofuran (THF, = 7) and benzonitrile (
= 26). Although hexamethylphosphoramide
(HMPA, = 30) is also a frequently used
solvent for electrochemical reduction, extreme
care must be used in handling it because of its
toxicity.
A supporting electrolyte for use in voltammetry
should fulfil the following conditions: (i) it
should be soluble in the solvent under study
and should dissociate into ions to give enough