1,2-Difluorobenzene

1,2-Difluorobenzene^[1]
Names
	Preferred IUPAC name 1,2-Difluorobenzene
	Other names o-Difluorobenzene; ortho-Difluorobenzene
Identifiers
CAS Number	367-11-3 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:38583 ;
ChemSpider	9325 ;
ECHA InfoCard	100.006.074
PubChem CID	9706;
UNII	AW7QGMW29C ;
CompTox Dashboard (EPA)	DTXSID2075390 ;
	InChI InChI=1S/C6H4F2/c7-5-3-1-2-4-6(5)8/h1-4H Key: GOYDNIKZWGIXJT-UHFFFAOYSA-N ; InChI=1/C6H4F2/c7-5-3-1-2-4-6(5)8/h1-4H Key: GOYDNIKZWGIXJT-UHFFFAOYAN;
	SMILES Fc1ccccc1F;
Properties
Chemical formula	C6H4F2
Molar mass	114.093 g/mol
Appearance	colorless liquid
Density	1.1599 g/cm3
Melting point	−34 °C (−29 °F; 239 K)
Boiling point	92 °C (198 °F; 365 K)
Solubility in water	(insoluble) 1.14 g/L
Related compounds
Related compounds	1,2-Dichlorobenzene
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

1,2-Difluorobenzene, also known as DFB, is an aromatic compound with formula C₆H₄F₂. 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.^[2]

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:^[3]

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.^[4]

Laboratory applications

Organometallic derivatives of 1,2-difluorobenzene have been well developed. It is found to be a weaker base than benzene.^[5]

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.^[6]

It has anaesthetic properties.^[7]

1,2-Difluorobenzene can be acylated to 3',4'-difluoropropiophenone.^[8]

References

^ David R. Lide, ed., CRC Handbook of Chemistry and Physics, 89th Edition (Internet Version 2009), CRC Press/Taylor and Francis, Boca Raton, FL.
^ Pike, Sebastian D.; Crimmin, Mark R.; Chaplin, Adrian B. (2017). "Organometallic chemistry using partially fluorinated benzenes" (PDF). Chemical Communications. 53 (26): 3615–3633. doi:10.1039/C6CC09575E. PMID 28304406.
^ Yu, Zhiqun; Lv, Yanwen; Yu, Chuanming (2012). "A Continuous Kilogram-Scale Process for the Manufacture of o-Difluorobenzene". Organic Process Research & Development. 16 (10): 1669–1672. doi:10.1021/op300127x.
^ Siegemund, Günter; Schwertfeger, Werner; Feiring, Andrew; Smart, Bruce; Behr, Fred; Vogel, Herward; McKusick, Blaine (2000). "Fluorine Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a11_349. ISBN 3527306730.
^ Pike, Sebastian D.; Crimmin, Mark R.; Chaplin, Adrian B. (2017). "Organometallic chemistry using partially fluorinated benzenes" (PDF). Chemical Communications. 53 (26): 3615–3633. doi:10.1039/c6cc09575e. PMID 28304406.
^ O'toole, Terrence R.; Younathan, Janet N.; Sullivan, B. Patrick; Meyer, Thomas J. (1989). "1,2-Difluorobenzene: a relatively inert and noncoordinating solvent for electrochemical studies on transition-metal complexes". Inorganic Chemistry. 28 (20): 3923. doi:10.1021/ic00319a032.
^ "1,2-Difluorobenzene". PubChem. Retrieved 11 February 2021.
^ GB 1140754, Danilewicz, John Christopher & Szelke, Michael, "3,4-difluorophenyl compounds", published 1969-01-22, assigned to Pfizer Ltd.

[1] David R. Lide, ed., CRC Handbook of Chemistry and Physics, 89th Edition (Internet Version 2009), CRC Press/Taylor and Francis, Boca Raton, FL.

[2] Pike, Sebastian D.; Crimmin, Mark R.; Chaplin, Adrian B. (2017). "Organometallic chemistry using partially fluorinated benzenes" (PDF). Chemical Communications. 53 (26): 3615–3633. doi:10.1039/C6CC09575E. PMID 28304406.

[3] Yu, Zhiqun; Lv, Yanwen; Yu, Chuanming (2012). "A Continuous Kilogram-Scale Process for the Manufacture of o-Difluorobenzene". Organic Process Research & Development. 16 (10): 1669–1672. doi:10.1021/op300127x.

[4] Siegemund, Günter; Schwertfeger, Werner; Feiring, Andrew; Smart, Bruce; Behr, Fred; Vogel, Herward; McKusick, Blaine (2000). "Fluorine Compounds, Organic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a11_349. ISBN 3527306730.

[5] Pike, Sebastian D.; Crimmin, Mark R.; Chaplin, Adrian B. (2017). "Organometallic chemistry using partially fluorinated benzenes" (PDF). Chemical Communications. 53 (26): 3615–3633. doi:10.1039/c6cc09575e. PMID 28304406.

[6] O'toole, Terrence R.; Younathan, Janet N.; Sullivan, B. Patrick; Meyer, Thomas J. (1989). "1,2-Difluorobenzene: a relatively inert and noncoordinating solvent for electrochemical studies on transition-metal complexes". Inorganic Chemistry. 28 (20): 3923. doi:10.1021/ic00319a032.

[7] "1,2-Difluorobenzene". PubChem. Retrieved 11 February 2021.

[8] GB 1140754, Danilewicz, John Christopher & Szelke, Michael, "3,4-difluorophenyl compounds", published 1969-01-22, assigned to Pfizer Ltd.

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