The Use of Electron Paramagnetic Resonance in Organic Chemistry



The more recent applications of electron paramagnetic resonance (EPR) to organic chemistry include the investigation of triplet states, donor-acceptor complexes, short-lived free-radical intermediates, and reaction kinetics. The principles of the theoretical calculations required to obtain the maximum information from EPR spectra are outlined for free radicals containing π-electron systems. EPR intensities, line widths, hyperfine splitting, and g factors permit the determination of free-radical yields, ionic charges, rotation frequencies in rotamers, electron density distributions, electronegativities, intramolecular torsion angles, solvent effects (resulting from hydrogen bonding), and π-orbital energies. – The production of free radicals with the aid of initiation reaction in flow systems, by irradiation, and by electrolysis seems particularly promising.