Perfluorocarbons carbon-fluorine bonding

Perfluorocarbons are essentially inert to hydrolysis unless heated to very high temperatures, although it has been calculated that the free energy of hydrolysis of carbon tetrafluoride is exothermic by 304kJmoP [12], and the inertness therefore stems from a high activation barrier. The carbon backbone in a perfluorocarbon is shielded towards attack by nucleophiles by the non-bonding electron pairs associated with the many adjacent fluorine atoms, and this is undoubtedly a major factor contributing to the relative inertness of fluorocarbons. 

A carbon atom can be bonded to as many as four halogen atoms, so an enormous number of organic halides can exist. Completely fluorinated compounds are known as fluorocarbons or sometimes perfluorocarbons. The fluorocarbons are even less reactive than hydrocarbons. Saturated compounds in which all H atoms have been replaced by some combination of Cl and F atoms are called chlorofluorocarbons or sometimes freons. These compounds were widely used as refrigerants and as propellants in aerosol cans. However, the release of chlorofluorocarbons into the atmosphere has been shown to be quite damaging to the earth s ozone layer. Since January 1978, the use of chlorofluorocarbons in aerosol cans in the United States has been banned, and efforts to develop both controls for existing chlorofluorocarbons and suitable replacements continue. The production and sale of freons have been banned in many countries. 

Fluorine substitution on carbon confers particular reactivity because of its particular properties Fluorine as the most electronegative element forms very strong CF bonds which are sized to "cover" perfluorocarbons tightly. Polytetrafluoroethylene (Teflon) is one practical example illustrating the exceptional chemical and thermal stability of saturated perfluorocarbons in a sharp contrast to explosive tetrafluoroethylene or to fluoroacetylenes. 

R Metrangolo, W. Panzeii, F. Recupero, G. Resnati, Perfluorocarbon-hydro-carbon self-assembly. Part 16. NMR smdy of the halogen bonding between halo-perfluorocarbons and heteroatom containing hydrocarbons, J. Fluorine Chem. 2002,114,27. 

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