Fluorine-18 is a particularly useful tracer isotope because its substitution for hydrogen in organic molecules generally does not alter their biological properties from those of the parent compounds,* since the size and energy of the CF bond is comparable to that of the CH bond. Arylsilanes react with electrophilic halogens such as Cl2, Br2, and I2 to give the corresponding aryl halides. 3 Perhaps because of the high reactivity of F2 however, its ...
