Early contributions to the chemistry of organic radical ions.

Several organic reactions discovered in the nineteenth century may have involved organic radical ions. For example, the radical anion of benzil can be traced back 150 years to the work of Auguste Laurent. Radical cations of the p-phenylene-diamines originate in the laboratory of Adolph von Baeyer in 1875. However, the correct chemical composition and the true nature of these species were not recognized until well into the twentieth century. This historical sketch is intended as a contribution to a Tetrahedron Symposium in Print on organic radical ions.