Pentafluorobenzoic acid
Names | |
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IUPAC name
2,3,4,5,6-pentafluorobenzoic acid | |
Other names
perfluorobenzoic acid | |
Identifiers | |
602-94-8 | |
3D model (Jmol) | Interactive image |
2054395 | |
ChemSpider | 11277 |
ECHA InfoCard | 100.009.115 |
2054395 | |
PubChem | 24898625 |
RTECS number | Drug |
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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 |
Hazards | |
NFPA 704 | |
Flash point | 87 °C (189 °F; 360 K) |
Related compounds | |
Related carboxylic acids |
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 2 3 Prakash, G. K. S.; Hu, J. "Pentafluorobenzoic Acid" e-EROS Encyclopedia of Reagents for Organic Synthesis, 2005. doi:10.1002/047084289X.rn00682
- ↑ Haper, R. J.; Jr; Soloski, E. J.; Tamborski, C. (1964). "Reactions of Organometallics with Fluoroaromatic Compounds". J. Org. Chem. 29: 2385. doi:10.1021/jo01031a067.
- ↑ 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