The addition of elemental fluorine to the carbon-carbon double bond in a variety of olefinic substrates proceeds in a stereoselective syn manner. The addition of a proton donor to the conventional CHC13-CFC13 solvent system suppresses radical processes usually resulting in tar formation so the slower ionic type of addition of F2 to the double bond takes place. Rapid collapse of the ion pair involving the a-fluoro carbocation ion is believed to account ...
