2016-05-10
Hydrofluorocarbons, organic compounds that contain only one or a few fluorine atoms, are the more common type of organofluorine compounds. Used as refrigerants in place of the older chlorofluorocarbons such as Freon-12, they do not harm the ozone layer if they do not contain chlorine or bromine. However, their atmospheric concentrations are rapidly increasing, causing international concern about a different process: their rising contribution to anthropogenic radiative forcing emissions (i.e., greenhouse gas global warming). Fluorocarbons with few C-F bonds behave similarly to the parent hydrocarbons, but their reactivity can be altered significantly. For example, both uracil and 5-fluorouracil are colourless, high-melting crystalline solids, but the latter is a potent anti-cancer drug. The use of the C-F bond in pharmaceuticals is predicated on this altered reactivity. Several drugs and agrochemicals contain only one fluorine center or one trifluoromethyl group.
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