Biphenyl


Biphenyl
Biphenyl
Identifiers
CAS number 92-52-4 YesY
ChemSpider 6828 YesY
UNII 2L9GJK6MGN YesY
KEGG C06588 YesY
ChEBI CHEBI:17097 YesY
ChEMBL CHEMBL14092 YesY
Jmol-3D images Image 1
Properties
Molecular formula C12H10
Molar mass 154.21 g mol−1
Appearance colorless crystals
Density 1.04 g/cm3
Melting point

68.93 °C, 342 K, 156 °F

Boiling point

256 °C, 529 K, 493 °F

Solubility in water Insoluble
Hazards
EU Index 601-042-00-8
EU classification Irritant (Xi)
Dangerous for
the environment (N)
R-phrases R36/37/38, R50/53
S-phrases (S2), S23, S60, S61
NFPA 704
NFPA 704.svg
1
1
0
Flash point 113 °C
Autoignition
temperature
540 °C
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Biphenyl (or diphenyl or phenylbenzene or 1,1'-biphenyl or lemonene) is an organic compound that forms colorless crystals. It has a distinctively pleasant smell. Biphenyl is an aromatic hydrocarbon with a molecular formula (C6H5)2. It is notable as a starting material for the production of polychlorinated biphenyls (PCBs), which were once widely used as dielectric fluids and heat transfer agents. Biphenyl is also an intermediate for the production of a host of other organic compounds such as emulsifiers, optical brighteners, crop protection products, and plastics.

Contents

Properties

Biphenyl occurs naturally in coal tar, crude oil, and natural gas and can be isolated from these sources via distillation. It can also be synthesized by using a grignard reagent such as phenylmagnesium bromide and reacting it with bromobenzene. Biphenyl is insoluble in water, but soluble in typical organic solvents. The biphenyl molecule consists of two connected phenyl rings. Lacking functional groups, it is fairly non-reactive. It will, however, participate in many of the reactions that are typical for benzene, for example, substitution reactions upon treatment with halogens in the presence of a Lewis acid.

Stereochemistry

Rotation about the single bond in biphenyl, and especially its ortho-substituted derivatives, is sterically hindered. For this reason, some substituted biphenyls show atropisomerism; that is, the individual C2-symmetric-isomers are optically stable. Some derivatives, as well as related molecules such as BINAP, find application as ligands in asymmetric synthesis. In the case of unsubstituted biphenyl, the equilibrium torsional angle is 44.4° and the torsional barriers are quite small, 6.0 kJ/mol at 0° and 6.5 kJ/mol at 90°.[1] Adding ortho substituents greatly increases the barrier: in the case of the 2,2'-dimethyl derivative, the barrier is 17.4 kcal/mol (72.8 kJ/mol).[2]

Biological aspects

Biphenyl prevents the growth of molds and fungus, and is therefore used as a preservative (E230, in combination with E231, E232 and E233), particularly in the preservation of citrus fruits during transportation.

It is mildly toxic, but can be degraded biologically by conversion into nontoxic compounds. Some bacteria are able to hydroxylate biphenyl and its polychlorinated biphenyls (PCBs). [3]

It is part of the active group in the antibiotic oritavancin.

Biphenyl compounds

Substituted biphenyls can be prepared synthetically by various coupling reactions including the Suzuki reaction and the Ullmann reaction and have many uses. Polychlorinated biphenyls were once used as cooling and insulating fluids and polybrominated biphenyls are flame retardants. The biphenyl motif also appears in drugs such as valsartan and telmisartan. The abbreviation E7 stands for a liquid crystal mixture consisting of several cyanobiphenyls with long aliphatic tails used commercially in liquid crystal displays. A variety of benzidine derivatives are used in dyes and polymers. Research into biphenyl liquid crystal candidates mainly focuses on molecules with highly polar heads (for example cyano or halide groups) and aliphatic tails.

See also

References

  1. ^ Mikael P. Johansson and Jeppe Olsen (2008). "Torsional Barriers and Equilibrium Angle of Biphenyl: Reconciling Theory with Experiment". J. Chem. Theory Comput. 4 (9): 1460. doi:10.1021/ct800182e. 
  2. ^ B. Testa (1982). "The geometry of molecules: basic principles and nomenclatures". In Christoph Tamm. Stereochemistry. Elsevier. pp. 18. 
  3. ^ Biphenyl degradation - Streptomyces coelicolor, at GenomeNet Database

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • biphenyl — [bī fen′əl, bīfē′nəl] n. DIPHENYL …   English World dictionary

  • Biphenyl — Strukturformel Allgemeines Name Biphenyl Andere Namen Dip …   Deutsch Wikipedia

  • biphenyl — /buy fen l, feen l/, n. Chem. a water insoluble, pleasant smelling, colorless powder or white scales, C12H10, composed of two phenyl groups, from which benzidine dyes are derived: used chiefly as a heat transfer agent and in organic synthesis.… …   Universalium

  • Biphenyl — Bi|phe|nyl 〈n. 11; unz.; Chem.〉 aromatische Verbindung aus zwei Phenylringen, die zur Konservierung von Zitrusfrüchten verwendet wird * * * Bi|phe|nyl [↑ bi (1) u. ↑ Phenyl] veraltetes Syn.: Diphenyl: H5C6 C6H5; farblose Krist., Smp. 71 °C, die… …   Universal-Lexikon

  • biphenyl — noun Etymology: International Scientific Vocabulary Date: circa 1923 a white crystalline hydrocarbon C6H5•C6H5 used especially as a heat transfer medium and in organic synthesis; also a derivative of biphenyl …   New Collegiate Dictionary

  • Biphenyl-2-ol — Strukturformel Allgemeines Name 2 Phenylphenol Andere Namen E 231 …   Deutsch Wikipedia

  • biphenyl — noun a) A colourless solid hydrocarbon, CH, consisting of two benzene rings linked together halogenated biphenyls b) Any substituted or otherwise altered version of biphenyl, such as PCBs …   Wiktionary

  • biphenyl — bifenilas statusas T sritis chemija formulė (C₆H₅)₂ atitikmenys: angl. biphenyl rus. бифенил …   Chemijos terminų aiškinamasis žodynas

  • biphenyl — SYN: diphenyl. polychlorinated b. (PCB) b. in which some or all of the hydrogen atoms attached to ring carbons are replaced by chlorine atoms; a probable human carcingogen and teratogen. * * * bi·phe·nyl ( )bī fen əl, fēn n a white crystalline… …   Medical dictionary

  • Biphenyl — Bi|phe|nyl 〈n.; Gen.: s, Pl.: e; Chemie〉 kristallisierender Kohlenwasserstoff, der u. a. zur Konservierung von Zitrusfrüchten verwendet wird [Etym.: <Bi… + Phenyl] …   Lexikalische Deutsches Wörterbuch


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.