3D model (JSmol)
CompTox Dashboard (EPA)
|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|R-phrases (outdated)||R36, R37, R38|
|S-phrases (outdated)||S16, S26, S36|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Its melting point is -44 °C, which is lower than that of benzene, as a result of the reduced symmetry of the molecule compared to benzene. In contrast, the boiling points of PhF and benzene are very similar, differing by only 4 °C. It is considerably more polar than benzene, with a dielectric constant of 5.42 compared to 2.28 for benzene at 298 K.
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 piperidine triazene, 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
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.
- Table of Dielectric Constants of Pure Liquids. National Bureau of Standards. 1951.
- Flood, D. T. (1943). "Fluorobenzene". Organic Syntheses.; Collective Volume, 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.