1,2-Difluorobenzene

1,2-Difluorobenzene, also known as DFB, is an aromatic compound with formula C$6$H$4$F$2$. This colorless flammable liquid is a solvent used in the electrochemical studies of transition metal complexes. Compared to most conventional halogenated aliphatic and aromatic solvents, it possesses an exceptionally high dielectric constant (ε0 = 13.8 at 300 K). Thus, it can be a suitable solvent for cationic, and/or highly electrophilic organometallic complexes.

Synthesis
Difluorobenzenes can be prepared by the Balz-Schiemann reaction, which entails conversion of diazonium tetrafluoroborate salts to their fluorides. The synthesis of 1,2-difluorobenzene starts with 2-fluoroaniline:
 * C6H4F(NH2) + HNO2  +  HBF4  ->  [C6H4F(N2)]BF4  +  2 H2O
 * [C6H4F(N2)]BF4 -> C6H4F2  +  N2  +  BF3

The syntheses of 1,3- and 1,4-difluorobenzene proceed respectively from 1,3- and 1,4-diaminobenzene, which are doubly diazotized.

Laboratory applications
Organometallic derivatives of 1,2-difluorobenzene have been well developed. It is found to be a weaker base than benzene.

1,2-Difluorobenzene has been used as solvent for the electrochemical analysis of transition metal complexes. It is relatively chemically inert, weakly coordinating and has a relatively high dielectric constant. It is a weakly coordinating for metal complexes, in contrast to acetonitrile, DMSO, and DMF.

It has anaesthetic properties.

1,2-Difluorobenzene can be acylated to 3',4'-difluoropropiophenone.