|Density||1.025 g/mL, liquid|
|Melting point||−44 °C (−47 °F; 229 K)|
|Boiling point||84 to 85 °C (183 to 185 °F; 357 to 358 K)|
|R-phrases||R36, R37, R38|
|S-phrases||S16, S26, S36|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Fluorobenzene is the chemical compound with the formula C6H5F, often abbreviated PhF. This species is a derivative of benzene, with a single fluorine atom attached. Its melting point is -44 °C, which is lower than that of benzene, indicative of the remarkable effect of fluorination on the intermolecular interactions as seen throughout organofluorine chemistry. In contrast, the boiling points of PhF and benzene differ by only 4 °C.
According to the procedure, solid [PhN2]BF4 is heated with a flame to initiate an exothermic reaction that affords two volatile products, PhF and BF3, which are readily separated because of their differing boiling points.
PhF was first reported in 1886 by O. Wallach at the University of Bonn, who prepared the compound in two steps, starting also with a phenyldiazonium salt. The diazonium chloride was first converted to its piperidinide, which in turn was cleaved using hydrofluoric acid.
- [PhN2]Cl + 2 C5H10NH → PhN=N-NC5H10 + [C5H10NH2]Cl
- PhN=N-NC5H10 + 2 HF → PhF + N2 + [C5H10NH2]F
An interesting historical note: in Wallach’s era, the element fluorine was symbolized with “Fl”. Thus, his procedure is subtitled “Fluorbenzol, C6H5Fl”.
PhF is a relatively inert compound because the C–F bond is very strong. PhF is a useful solvent for highly reactive species, but a metal complex has been crystallized.
Fluorination of fluorobenzene gives mainly 1,2-difluorobenzene.
- Flood, D. T. (1943). "Fluorobenzene". Org. Synth.; Coll. Vol. 2, p. 295.
- Wallach, O. “Über einen Weg zur leichten Gewinnung organischer Fluorverbindungen” (Concerning a method for easily preparing organic fluorine compounds) Justus Liebig's Annalen der Chemie, 1886, Volume 235, p. 255–271; doi:10.1002/jlac.18862350303
- R.N. Perutz and T. Braun “Transition Metal-mediated C–F Bond Activation” Comprehensive Organometallic Chemistry III, 2007, Volume 1, p. 725–758; doi:10.1016/B0-08-045047-4/00028-5.