Perfluorination and Selective Direct Fluorination

Shortly after their first isolation of elemental fluorine in 1886, Moissan and his coworkers treated several organic substrates with this highly reactive gas. All these experiments, either at room temperature or at liquid nitrogen temperature, resulted in sometimes violent explosions. No major defined reaction products could be isolated. 

The first defined fluoroaliphatic compounds obtained by direct fluorination of organic substrates in liquid reaction media were characterized by Bockemiiller [3] in the early 1930s and published with his thermochemical analysis. To control the immense reaction enthalpy the fluorine gas was diluted with nitrogen or carbon dioxide. The organic substrate was dissolved in a cooled inert solvent, for example CCI4 or CFjClj. A similar line of work was pursued in the United States by L. A. Bigelow [4] who studied the reaction of arenes with fluorine gas. 

A modern, improved version of this general method, the LaMar (Lagow-Mar-grave) process, uses a nickel reactor with different temperature zones and silver- 

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The first pure and fully characterized perjluorocarhons (PFC) were obtained by the reaction of graphite with fluorine gas, yielding mainly carbon tetrafluoride [10]. An improved procedure, less prone to accidents, was reported by Simons and Block in 1937 - passage of fluorine over graphite impregnated with catalytic amounts of mercuric chloride furnished a mixture of various per-fluorocarbons in a controllable and reproducible reaction, proceeding steadily and without explosions [11]. 

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