Organofluorine Chemistry: Nomenclature and Historical Landmarks

Abstract

Fluorine—the superhdlogen—is by no means a rare element: found only in the form of its mononuclidic 199F−919F−{}_9^{19}{F^ - } ion, it lies 13th in order of abundance of the elements in Earth’s crust, and therefore outranks chlorine and the other members of the “salt-forming” family (Cl, 20th; Br, 46th; I, 60th; Ar, the rarest element).1, 2a It is the most electronegative of all the chemical elements (Pauling values: F, 4.0; O, 3.4; Cl, 3.2; C, 2.6: H, 2.2) and easily the most reactive—a fact superbly underscored in the early 1960s by the direct synthesis of the noble-gas fluorides XeFx (x = 2, 4, 6), 1 the difluoride being obtainable simply by exposing a mixture of xenon and fluorine to sunlight.2b