Carbon monofluoride

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Carbon monofluoride (CF, CFx, or (CF)x), also called polycarbon monofluoride (PMF), polycarbon fluoride, poly(carbon monofluoride), and graphite fluoride, is a material formed by high-temperature reaction of fluorine gas with graphite, charcoal, or pyrolytic carbon powder.[1] It is a highly hydrophobic microcrystalline powder. Its CAS number is [51311-17-2]. In contrast to graphite intercalation compounds it is a covalent graphite compound.

Carbon is stable in fluorine atmosphere up to about 400 °C, but between 420-600 °C reaction takes place to give substoichiometric carbon monofluoride, CF0.68 appearing dark grey. With increasing temperature and fluorine pressure stoichiometries up to CF1.12 are formed. With increasing fluorine content the colour changes from dark grey to cream white indicating the loss of the aromatic character. The fluorine atoms are located in an alternating fashion above and under the former graphene plane, which is now buckled due to formation of covalent carbon-fluorine bonds. Reaction of carbon with fluorine at even higher temperature successively destroys the graphite compound to yield a mixture of gaseous fluorocarbons such as tetrafluorocarbon, CF4, and tetrafluoroethylene, C2F4.[2]

In a similar fashion the recently found carbon allotrope fullerene, C60 reacts with fluorine gas to give fullerene fluorides with stoichiometries up to C60F48.[3]

A precursor of carbon monofluoride is the fluorine-graphite intercalation compound, also called fluorine-GIC.

Other intercalation fluorides of carbon are

  • poly(dicarbon fluoride) ((C2F)n);
  • tetracarbon monofluoride (TCMF, C4F).

Graphite fluoride is a procursor for preparation of graphene fluoride by a liquid phase exfoliation.[4]

Application

Carbon monofluoride is used as a high energy density cathode material in lithium batteries of the "BR" type. Other uses are a wear reduction additive for lubricants, and weather-resistant additive for paints. Graphite fluoride is also used as both oxidizing agent and combustion modifier in rocket propellants and pyrolants.[5]

References

A useful monograph on graphite fluorides has been written by Watanabe and coworkers [6]

  1. ↑ Ernst-Christian Koch (3 April 2012). Metal-Fluorocarbon Based Energetic Materials. John Wiley & Sons. pp. 25–27. ISBN 978-3-527-32920-5. Retrieved 16 September 2012. 
  2. ↑ BBC - h2g2 - Carbon and its Inorganic Compounds
  3. ↑ O. V. Boltalina et al. Two isomers of C60F48: An Indented Fullerene, Angew. Chem. Int. Ed. 40 2001, 2285
  4. ↑ Radek Zboril, Frantisek Karlicky, A.B. Bourlinos, T.A. Steriotis, A.K. Stubos, V. Georgakilas, K. Safarova, D. Jancik, C. Trapalis, and Michal Otyepka (2010). "Graphene Fluoride: A Stable Stoichiometric Graphene Derivative and its Chemical Conversion to Graphene". Small 6 (24): 2885–2891. doi:10.1002/smll.201001401. 
  5. ↑ E.-C. Koch, Metal/Fluorocarbon Pyrolants: VI. Combustion Behaviour and Radiation Properties of Magnesium/Poly(Carbon Monofluoride) Pyrolant, Prop.,Expl.,Pyrotech. 30 2005, 209
  6. ↑ N. Watanabe T. Nakajima,H. Touhara, Graphite Fluorides, Elsevier, 1988

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