Pentafluorobenzoic acid

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Pentafluorobenzoic acid
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Names
IUPAC name
2,3,4,5,6-pentafluorobenzoic acid
Other names
perfluorobenzoic acid
Identifiers
602-94-8
2054395
ChemSpider 11277
2054395
Jmol 3D model Interactive image
PubChem 24898625
RTECS number Drug
  • InChI=1S/C7HF5O2/c8-2-1(7(13)14)3(9)5(11)6(12)4(2)10/h(H,13,14)
    Key: YZERDTREOUSUHF-UHFFFAOYSA-N
  • InChI=1/C7HF5O2/c8-2-1(7(13)14)3(9)5(11)6(12)4(2)10/h(H,13,14)
    Key: YZERDTREOUSUHF-UHFFFAOYAQ
  • Fc1c(c(F)c(F)c(F)c1F)C(=O)O
Properties
C7HF5O2
Molar mass 212.076 g/mol
Appearance White crystalline powder
Density 1.942 g/cm^3
Melting point 100-102
Boiling point 220
very soluble
log P 2.06
Vapor pressure 0.07 (25 C)
Acidity (pKa) 1.60
Vapor pressure {{{value}}}
Related compounds
benzoic acids,
Nitrobenzoic acids
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Pentafluorobenzoic acid (PFBA) is an organofluorine compound with the formula C6F5CO2H. It is a white crystalline powder that has a high solubility in water. Its pKa of 1.48 indicates that it is a strong acid.[1]

Preparation

Pentafluorobenzoic acid is prepared by treating pentafluorophenyllithium (or pentafluorophenyl Grignard reagent) with carbon dioxide. These reagents are usually prepared in situ from pentafluorobenzene and bromopentafluorobenzene.[1][2]

It arises via the reaction of perfluorotoluene with trifluoroacetic acid and antimony pentafluoride.[3]

Substitution reactions

Substitution of fluoride occurs typically at the para position. This reaction has been used to anchor the −C6F4CO2H group to surfaces. Magnesium methoxide results in ortho methoxylation. Cleavage of this ether gives tetrafluorosalicylic acid. Via similar ortho-directed reactivity, nickel complexes catalyse the defluoridation of 2 and 5 positions. Without nickel, defluoridation occurs with para-selectivity.[1]

References

  1. 1.0 1.1 1.2 Prakash, G. K. S.; Hu, J. "Pentafluorobenzoic Acid" e-EROS Encyclopedia of Reagents for Organic Synthesis, 2005. doi:10.1002/047084289X.rn00682
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  3. Yaroslav V. Zonov, Victor M. Karpov, Vyacheslav E. Platonov "Transformation of perfluorinated benzocycloalkenes and alkylbenzenes to their carbonyl derivatives under the action of CF3COOH/SbF5" Journal of Fluorine Chemistry, 2007, vol. 128, pp. 1058-1064. doi:10.1016/j.jfluchem.2007.05.020