Benzil

Benzil

Names
Preferred IUPAC name Diphenylethanedione
Systematic IUPAC name 1,2-Diphenylethane-1,2-dione
Other names Diphenylethane-1,2-dione Benzil Dibenzoyl Bibenzoyl Diphenylglyoxal
Identifiers
CAS Number	134-81-6 Y
3D model (JSmol)	Interactive image Interactive image
ChEBI	CHEBI:51507 Y
ChemSpider	8329 Y
ECHA InfoCard	100.004.689
PubChem CID	8651
InChI InChI=1S/C14H10O2/c15-13(11-7-3-1-4-8-11)14(16)12-9-5-2-6-10-12/h1-10H Y Key: WURBFLDFSFBTLW-UHFFFAOYSA-N Y InChI=1/C14H10O2/c15-13(11-7-3-1-4-8-11)14(16)12-9-5-2-6-10-12/h1-10H Key: WURBFLDFSFBTLW-UHFFFAOYAZ
SMILES O=C(C(=O)c1ccccc1)c2ccccc2 c1ccc(cc1)C(=O)C(=O)c2ccccc2
Properties
Chemical 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	94.0 to 96.0 °C; 201.2 to 204.8 °F; 367.1 to 369.2 K
Boiling point	346.0 to 348.0 °C; 654.8 to 658.4 °F; 619.1 to 621.1 K
Solubility in water	insoluble
Solubility in ethanol	soluble
Solubility in diethyl ether	soluble
Solubility in benzene	soluble
Magnetic susceptibility (χ)	-118.6·10−6 cm3/mol
Structure
Crystal structure	P31,221
Dipole moment	3.8 D
Hazards
Main hazards	Irritant
NFPA 704	1 2 0
Related compounds
Related diketones	biacetyl
Related compounds	benzophenone glyoxal bibenzil
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
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.

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°. In less hindered analogues (glyoxal, biacetyl, oxalic acid derivatives), the (RCO)₂ group adopts a planar, anti-conformation.

Most benzil is used 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 potent inhibitor of human carboxylesterases, enzymes involved in the hydrolysis of carboxylesters and many clinically used drugs.

Benzil is a relatively poor photoinitiator, and is seldom used. It absorbs at the 260 nm wavelength. It undergoes photobleaching, which allows the curing light to reach deeper layers of the material on longer exposure.

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.