Fluorobenzene

Structural formula
General
Surname	Fluorobenzene
other names	Monofluorobenzene Phenyl fluoride Fluorobenzene
Molecular formula	C 6 H 5 F
Brief description	colorless liquid, benzene-like odor
External identifiers / databases
CAS number 462-06-6 EC number 207-321-7 ECHA InfoCard 100.006.657 PubChem 10008 Wikidata Q420820
properties
Molar mass	96.10 g mol −1
Physical state	liquid
density	1.03 g cm −3 (20 ° C)
Melting point	−42 ° C
boiling point	85 ° C
Vapor pressure	81.3 hPa (20 ° C) 130 hPa (30 ° C) 200 hPa (40 ° C) 300 hPa (50 ° C)
solubility	almost insoluble in water (1.54 g l −1 at 30 ° C)
Refractive index	1.4684 (30 ° C)
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 225-319-412 P: 210-273-305 + 351 + 338
Toxicological data	4400 mg kg −1 ( LD 50 ,  rat ,  oral )
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . Refractive index: Na-D line , 20 ° C

Fluorobenzene (C ₆ H ₅ F) is an aromatic halogenated hydrocarbon . The molecule is structured like benzene ; one of the six hydrogen atoms in benzene has been replaced by a fluorine atom.

presentation

A representation by halogenation as with chlorobenzene and bromobenzene is not possible. The synthesis succeeds by means of the Schiemann reaction . The synthesis begins with a diazotization of aniline . By adding a sodium tetrafluoroborate solution (NaBF ₄ ), the diazonium salt is precipitated as tetrafluoroborate, and the precipitate is washed, dried and carefully heated to react.

${\displaystyle \mathrm {Ph{-}N\equiv N^{+}[BF_{4}]^{-}\longrightarrow Ph{-}F+N_{2}\uparrow +BF_{3}} }$

The reaction is also successful with aqueous hexafluorophosphoric acid (HPF ₆ ).

properties

Fluorobenzene is a colorless, flammable liquid and largely non-polar, therefore very poorly soluble in water , and soluble in alcohols , benzene and ethers . Starting from benzene to fluorobenzene, the melting point drops significantly from +5.5 to −42 ° C - due to the introduction of a single substituent into the highly symmetrical benzene molecule. In contrast, the boiling point hardly rises, from 80.1 to 85 ° C.

Fluorobenzene forms highly flammable vapor-air mixtures. The compound has a flash point of −15 ° C. The explosion range is between 1.3 vol.% As the lower explosion limit (LEL) and 8.9 vol.% As the upper explosion limit (UEL). The ignition temperature is 630 ° C. The substance therefore falls into temperature class T1.

use

Fluorobenzene is a relatively inert compound. It serves both as a good solvent for highly reactive components, but also forms crystallizable metal complexes.

Structure of [(C ₅ Me ₅ ) ₂ Ti (FC ₆ H ₅ )] ⁺ , a coordination complex of fluorobenzene.

By bromination of fluorobenzene in the presence of a catalyst may be 4-bromofluorobenzene be obtained.

Individual evidence

1. ↑ ^{a b c d e f g h i j k l m n o} Entry on fluorobenzene in the GESTIS substance database of the IFA , accessed on August 21, 2017(JavaScript required) .
2. ↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Physical Constants of Organic Compounds, pp. 3-260.
3. ↑ DT Flood: Fluorobenzene In: Organic Syntheses . 13, 1933, p. 46, doi : 10.15227 / orgsyn.013.0046 ; Coll. Vol. 2, 1943, p. 295 ( PDF ).
4. ^ ^{A b} E. Brandes, W. Möller: Safety-related parameters - Volume 1: Flammable liquids and gases , Wirtschaftsverlag NW - Verlag für neue Wissenschaft GmbH, Bremerhaven 2003.
5. ↑ RN Perutz, T. Braun: Transition Metal-mediated C – F Bond Activation , in: Comprehensive Organometallic Chemistry III , 2007 , 1 , pp. 725-758; doi : 10.1016 / B0-08-045047-4 / 00028-5 .
6. ↑ US Department of Health and Human Services: 4-Bromofluorobenzene CAS No. 460-00-4 Review of Toxicological Literature , accessed January 7, 2019.

literature

• O. Wallach: About a way to easily obtain organic fluorine compounds , in: Justus Liebigs Annalen der Chemie , 1886 , 235 , pp. 255-271; doi : 10.1002 / jlac.18862350303 .