Preparation of Fluorocarbons by Catalytic Fluorination of Hydrocarbons

Abstract

THE technique for catalytic fluorination has been iniproved to such an extent that a desired saturated fluorocarbon may be produced in moderate to high yield b v the reaction of the corresponding hydrocarbon with elementary fluorine. The hydrocarbon vapor and the fluorine are each diluted by nitrogen and are gradually mixed iu the presence of fine copper turnings or ribbon coated with a thin layer of silver fluorides. This procedure has been used to produce straight or branchedchain fluorocarbons ranging from perfluorobutane to perfluorohexadecane and naphthenic fluorocarbons from C6Flz to Cl8F30. Volatile hydrocarbon lubricating oils have also been fluorinated. It appears probable that the fluorocarbons are produced by the action of the fluorinating agent, AgFz, upon the hydrocarbon vapor and that the supply of the silver difluoride in maintained by the reaction: 2AgFz f Fz ---.f 2AgF2.

Fluorine Compounds, Organic

“…Direct fluorination can also be carried out in the gas phase in a tubular reactor packed with silver-or gold-plated copper turnings [20]. Specialized methods are based on LaMar fluorination [17], aerosol fluorination [21], porous-tube fluorination [22], and jet fluorination [23]; high product selectivities are achieved at a laboratory scale.…”

“…81% are reported for batch operations on a 1-t scale. (20) In a continuous process the three exothermic steps are controlled by separation; i.e., hydrofluorination of the aromatic amine, diazotization, and thermal decomposition [367]. This permits safe operation on a large scale.…”

Organic Fluorine Chemistry

“…Noncatalytic fluorinations with elemental fluorine require a special type of a Chapter 1 cold-flame burner allowing fast mixing of the reaction components [6]. Catalytic fluorinations with elemental fluorine are carried out in vertical reactors filled with the appropriate substrate coated with the metal catalyst [7]. Reactions of organic compounds with high-valency metal fluorides such as cobalt trifluoride are carried out in rotary horizontal tubes fitted with paddle stirrers (Fig.…”

“…N oncatalytic fluorination gives inferior yields to the catalytic process carried out over copper coated with silver or gold. These metals transiently form fluorides which pass fluorine onto the organic material [83][84][85]. (83) F2.…”

Silverland: the Realm of Compounds of Divalent Silver—and Why They are Interesting

“…Such reactions may simply be conducted in a stream of F 2 gas, with a trace amount of Ag 1+ as a catalyst precursor (AgF 2 forms in situ). However, many interesting chemical properties of AgF 2 were disclosed only after the 2nd World War [14], since strong fluorinating agents were used to prepare UF 6 for its further isotope separation during the Manhattan Project. Nowadays, AgF 2 finds wide use in laboratory synthesis (particularly in organic chemistry) with the annual production of ca.…”