2,2'-Bithiophene

2,2'-Bithiophene
Names
	Preferred IUPAC name 2,2′-Bithiophene
	Other names 2,2′-Bisthiophene, 2,2′-dithienyl, 2,2′-bithienyl, 2-(2-thienyl)thiophene
Identifiers
CAS Number	492-97-7;
3D model (JSmol)	Interactive image;
ChemSpider	61428;
ECHA InfoCard	100.007.062
EC Number	207-767-2;
PubChem CID	68120;
UNII	8CTS9HJ7L6 ;
CompTox Dashboard (EPA)	DTXSID8060084 ;
	InChI InChI=1S/C8H6S2/c1-3-7(9-5-1)8-4-2-6-10-8/h1-6H Key: OHZAHWOAMVVGEL-UHFFFAOYSA-N; InChI=1/C8H6S2/c1-3-7(9-5-1)8-4-2-6-10-8/h1-6H Key: OHZAHWOAMVVGEL-UHFFFAOYAB;
	SMILES c1cc(sc1)c2cccs2;
Properties
Chemical formula	C8H6S2
Molar mass	166.26 g·mol−1
Appearance	Colorless crystals
Density	1.44 g/cm3
Melting point	31.1 °C (88.0 °F; 304.2 K)
Boiling point	260 °C (500 °F; 533 K)
Structure
Crystal structure	Monoclinic
Space group	P21/c
Lattice constant	a = 7.873 A, b = 5.771 A, c = 8.813 A α = 90°, β = 107.07°, γ = 90°
Coordination geometry	2
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

2,2′-Bithiophene is the organic compound. It is a colorless solid, although commercial samples are often greenish.^[3] It is the most common of the three isomers with formula (C₄H₃S)₂. The other two isomers have the connectivity 2,3′- and 3,3′-. The compound is typically prepared by cross-coupling starting from 2-halothiophenes.

X-ray crystallography shows that the two rings are coplanar,^[3] unlike the situation for biphenyl.

Occurrence

A number of bi- as well as terthiophenes exist naturally, invariably with substituents at the positions flanking sulfur. In terms of the biosynthesis, bithiophenes are proposed to be derived from polyacetylenic precursors, which in turn are the products of dehydrogenation of oleic acid. According to some hypotheses, these polyalkynes form labile 1,2-dithiins via a reaction with H₂S₂ or its equivalent.^[4]

References

^ ^a ^b Pelletier, M.; Brisse, F. (1994). "Bithiophene at 133 K". Acta Crystallographica Section C Crystal Structure Communications. 50 (12): 1942–1945. doi:10.1107/S010827019301011X.
^ ^a ^b Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. p. 3.58. ISBN 9781498754293.
^ ^a ^b Chaloner, P. A.; Gunatunga, S. R.; Hitchcock, P. B. (1994). "Redetermination of 2,2′-bithiophene". Acta Crystallographica C. C50 (12): 1941–2. doi:10.1107/S0108270194001149.
^ Kagan, J. (1991). "Naturally Occurring Di- and Trithiophenes. In: Fortschritte der Chemie organischer Naturstoffe / Progress in the Chemistry of Organic Natural Products". Fortschritte der Chemie organischer Naturstoffe / Progress in the Chemistry of Organic Natural Products. Vol. 56. pp. 87–169. doi:10.1007/978-3-7091-9084-5_2. ISBN 978-3-7091-9086-9. PMID 2050313.

[str-1] Pelletier, M.; Brisse, F. (1994). "Bithiophene at 133 K". Acta Crystallographica Section C Crystal Structure Communications. 50 (12): 1942–1945. doi:10.1107/S010827019301011X.

[crc-2] Haynes, William M., ed. (2016). CRC Handbook of Chemistry and Physics (97th ed.). CRC Press. p. 3.58. ISBN 9781498754293.

[Xray-3] Chaloner, P. A.; Gunatunga, S. R.; Hitchcock, P. B. (1994). "Redetermination of 2,2′-bithiophene". Acta Crystallographica C. C50 (12): 1941–2. doi:10.1107/S0108270194001149.

[4] Kagan, J. (1991). "Naturally Occurring Di- and Trithiophenes. In: Fortschritte der Chemie organischer Naturstoffe / Progress in the Chemistry of Organic Natural Products". Fortschritte der Chemie organischer Naturstoffe / Progress in the Chemistry of Organic Natural Products. Vol. 56. pp. 87–169. doi:10.1007/978-3-7091-9084-5_2. ISBN 978-3-7091-9086-9. PMID 2050313.

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