Fluorine is a highly corrosive, reactive gas. In its elemental form, fluorine is highly toxic and must be carefully handled. Fluorine is a necessary component of many pharmaceuticals, fine chemicals, and polymers. Fluorination reactions are designed to add fluorine to substrate molecules. There are a number of reagents available to accomplish fluorinations. A common fluorinating reagent is hydrofluoric acid, but it is also corrosive, reactive, and must be used with great care. The other issue with fluorinating with elemental fluorine or HF is specificity. They tend to be so effective at reacting with organics that it is difficult to control the position on which the fluorine atom inserts in a substrate molecule. A number of reagents have been developed that are more effective at providing controlled fluorinations. For example, DAST (diethylaminosulfur trifluoride) is commonly used to convert carbonyl and alcohols to their analogous fluoro derivatives. An even more benign reagent is SelectFluor [(1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2] octane bis(tetrafluoroborate)], which is an electrophilic fluorinating reagent that is easier to use, since it is nonvolatile and air/moisture stable.