CAS number 134-81-6 YesY
PubChem 8651
ChemSpider 8329 YesY
ChEBI CHEBI:51507 YesY
Jmol-3D images Image 1
Image 2
Molecular formula C14H10O2
Molar mass 210.23 g mol−1
Appearance yellow crystals or powder
Density 1.23 g/cm3, solid (1.255 g/cm3, x-ray)
Melting point

94.43-95.08 °C, 201.97-203.14 °F, 367-368 K

Boiling point

346- 348 °C, 654.8-658.4 °F, 619-621 K

Solubility in water insoluble
Solubility in benzene soluble
Crystal structure P31,221[1]
Dipole moment 3.8 D[2]
Main hazards Irritant
NFPA 704
NFPA 704.svg
Related compounds
Related diketones biacetyl
Related compounds benzophenone
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Benzil (systematically known as 1,2-diphenylethane-1,2-dione) is the organic compound with the formula (C6H5CO)2, generally abbreviated (PhCO)2. This yellow solid is one of the most common diketones. Its main use is as a photoinitiator in polymer chemistry.[3]



The compound's most noteworthy structural feature is the long carbon-carbon bond of 1.54 Å, which indicates the absence of pi-bonding between the two carbonyl centers. The PhCO centers are planar, but the pair of benzoyl groups are twisted with respect to the other with a dihedral angle of 117°.[4] In less hindered analogues (glyoxal, biacetyl, oxalic acid derivatives), the (RCO)2 groups adopts a planar, anti-conformation.


Most benzil is consumed for use in the free-radical curing of polymer networks. Ultraviolet radiation decomposes benzil, generating free-radical species within the material, promoting the formation of cross-links.


Benzil is a standard building block in organic synthesis. It condenses with amines to give diketimines ligands. A classic organic reaction of benzil is the benzilic acid rearrangement, in which base catalyses the conversion of benzil to benzilic acid. This reactivity is exploited in the preparation of the drug phenytoin. Benzil also reacts with 1,3-diphenylacetone in an aldol condensation to give tetraphenylcyclopentadienone.


Benzil is prepared from benzoin, which in turn is easily obtained via the benzoin condensation from benzaldehyde.[5]

PhC(O)CH(OH)Ph + 2 Cu2+ → PhC(O)C(O)Ph + 2 H+ + 2 Cu+


  1. ^ Acta Cryst. B43 398 (1987)
  2. ^ Spectrochim. Acta A60 (8-9) 1805 (2004)
  3. ^ Hardo Siegel, Manfred Eggersdorfer "Ketones" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, 2002 by Wiley-VCH, Wienheim. doi:10.1002/14356007.a15_077
  4. ^ Quang. Shen, Kolbjoern. Hagen "Gas-phase molecular structure and conformation of benzil as determined by electron diffraction" J. Phys. Chem., 1987, 91 (6), pp 1357–1360. doi:10.1021/j100290a017.
  5. ^ Clarke, H. T.; Dreger.E. E. (1941), "Benzil", Org. Synth., ; Coll. Vol. 1: 87 

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  • benzil — BENZÍL s.m. Radical univalent. – Din fr. benzyle. Trimis de paula, 02.06.2002. Sursa: DOOM  BENZÍL s.m. 1. Radical monovalent provenit din toluen prin îndepărtarea unui atom de hidrogen. (din fr. benzyle) 2. Substanţă aromatică, cristalizată,… …   Dicționar Român

  • benzil — bènzīl m <G benzíla> DEFINICIJA kem. C6H5CH2 , jednovalentni organski radikal SINTAGMA benzil alkohol kem. C6H5CH2OH, najjednostavniji aromatski alkohol, upotrebljava se u industriji parfema ETIMOLOGIJA benz …   Hrvatski jezični portal

  • benzil- — statusas T sritis chemija apibrėžtis Grupė. formulė C₆H₅CH₂– santrumpa( os) Bzl atitikmenys: angl. benzyl rus. бензил ryšiai: sinonimas – fenilmetil …   Chemijos terminų aiškinamasis žodynas

  • Benzil — Strukturformel Allgemeines Name Benzil Andere Namen Dibenzoyl …   Deutsch Wikipedia

  • Benzil — Ben|zil [↑ Benz u. ↑ il], das; s; Syn.: Bibenzoyl: H5C6 CO CO C6H5; hellgelbe Verb., Smp. 95 °C, die sich unter Baseneinfluss in ↑ Benzilsäure umwandelt. * * * Benzil   [arabisch] …   Universal-Lexikon

  • benzil — bibenzoilas statusas T sritis chemija formulė (C₆H₅CO)₂ atitikmenys: angl. benzil; bibenzoyl rus. бензил; бибензоил; дибензоил ryšiai: sinonimas – benzilas sinonimas – 1,2 difenil 1,2 etandionas …   Chemijos terminų aiškinamasis žodynas

  • benzil — noun The organic compound 1,2 diphenyl 1,2 ethanedione, a diketone used as an intermediate in organic synthesis and as a photoinitiator for free radical curing of polymer networks …   Wiktionary

  • benzil — ben|zil Mot Agut Nom masculí …   Diccionari Català-Català

  • benzíl — s. m., pl. benzíli …   Romanian orthography

  • benzil — ben·zil …   English syllables

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