Acid-base equilibria in organic solvents

Abstract

Cyclic voltammetry is applied to evaluate the relative basicity of some organic polar solvents of electroanalytical interest (nitromethane, acetonitrile, tetrahydrofuran, 1,2-dimethoxyethane, dimethylformamide, dimethyl sulphoxide and pyridine). For this purpose, anhydrous perchloric acid is electrogenerated in these solvents and the half-wave potentials of the redox couple H⁺/H₂ are recorded by referring them to a reference system independent of the nature of the solvent. The proton-basicity scale so obtained is compared with previous basicity series and the observed analogies and differences are discussed. The same procedure is also applied to evaluate, in the solvents mentioned, the relative strengths of some bases which can be used as titrants in nonaqueous media.