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| 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 | |
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3D model (JSmol) | |
| 608047 | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
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| ECHA InfoCard | 100.004.689 |
| EC Number |
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| RTECS number |
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| UNII | |
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| Properties | |
| C14H10O2 | |
| Molar mass | 210.232 g·mol−1 |
| Appearance | yellow crystalline powder |
| Density | 1.521 g/cm3, solid (1.255 g/cm3, x-ray)[1] |
| 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 |
| insoluble | |
| Solubility inethanol | soluble |
| Solubility indiethyl ether | soluble |
| Solubility inbenzene | soluble |
| −118.6·10−6 cm3/mol | |
| Structure | |
| P31,221[2] | |
| 3.8D[3] | |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards | Irritant |
| GHS labelling: | |
 | |
| Warning | |
| H315,H319,H335 | |
| P261,P264,P271,P280,P302+P352,P304+P340,P305+P351+P338,P312,P321,P332+P313,P337+P313,P362,P403+P233,P405,P501 | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | >3 g/kg (mouse, oral)[4] |
| Related compounds | |
Relateddiketones | diacetyl |
Related compounds | benzophenone glyoxal bibenzil |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Benzil (i.e.Bz2, systematically known as 1,2-diphenylethane-1,2-dione) is theorganic compound with the formula (C6H5CO)2, generally abbreviated (PhCO)2. This yellow solid is one of the most commondiketones. Its main use is as aphotoinitiator inpolymer chemistry.[5]
The compound's most noteworthy structural feature is the longcarbon-carbon bond of 1.54Å, 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 adihedral angle of 117°.[6] In lesshindered analogues (glyoxal,biacetyl,oxalic acid derivatives), the (RCO)2 group adopts a planar, anti-conformation.
Most benzil can be used as a photoinitiator in the free-radicalcuring ofpolymer networks. It absorbsultraviolet radiation at a wavelength of 260 nm, leading to decomposition with formation of free-radical species and formation ofcross-links within the material. However, it is a relatively poor photoinitiator, and is seldom used. It undergoesphotobleaching, which allows the curing light to reach deeper layers of the material on longer exposure.[7]Acetal derivatives, such as2,2-dimethoxy-2-phenylacetophenone, have better properties for this application.[7]
Benzil is a potentinhibitor of humancarboxylesterases,enzymes involved in the hydrolysis of carboxylesters and many clinically used drugs.[8]
Benzil is a standard building block inorganic synthesis. It condenses with amines to givediketimine ligands. A classicorganic reaction of benzil is thebenzilic acid rearrangement, in which base catalyses the conversion of benzil tobenzilic acid. This reactivity is exploited in the preparation of the drugphenytoin. Benzil also reacts with1,3-diphenylacetone in analdol condensation to givetetraphenylcyclopentadienone.
Benzil is prepared frombenzoin, for example withcopper(II) acetate:[9]
Other suitable oxidizing agents such asnitric acid (HNO3) are used routinely.
Iron(III) chloride (FeCl3) can be used as an inexpensive catalyst for this chemical conversion.[10]
