Benzophenone
| Benzophenone | |
|---|---|
 |
|
 |
|
 |
|
|
Diphenylmethanone |
|
|
Other names
Phenyl ketone; Diphenyl ketone; Benzoylbenzene |
|
| Identifiers | |
| CAS number | 119-61-9  |
| PubChem | 3102 |
| ChemSpider | 2991 |
| UNII | 701M4TTV9O |
| DrugBank | DB01878 |
| KEGG | C06354 |
| ChEBI | CHEBI:41308 |
| ChEMBL | CHEMBL90039 |
| Jmol-3D images | Image 1 |
|
|
|
|
| Properties | |
| Molecular formula | C13H10O |
| Molar mass | 182.22 g mol−1 |
| Appearance | White solid |
| Odor | Geranium-like[1] |
| Density | 1.11 g/cm3[1] |
| Melting point |
48.5 °C, 322 K, 119 °F ([1]) |
| Boiling point |
305.4 °C, 579 K, 582 °F ([1]) |
| Solubility in water | Insoluble[1] |
| Solubility in organic solvents | 1 g/ 7.5 mL in ethanol[1] 1 g/ 6 mL in diethyl ether[1] |
| Hazards | |
| MSDS | External MSDS by JT Baker |
| Main hazards | Harmful (XN) |
| NFPA 704 |
 1
3
0
|
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
|
| Infobox references | |
Benzophenone is the organic compound with the formula (C6H5)2CO, generally abbreviated Ph2CO. Benzophenone is a widely used building block in organic chemistry, being the parent diarylketone.
Contents |
Uses [edit]
Benzophenone can be used as a photo initiator in UV-curing applications such as inks, imaging, and clear coatings in the printing industry. Benzophenone prevents ultraviolet (UV) light from damaging scents and colors in products such as perfumes and soaps. It can also be added to the plastic packaging as a UV blocker. Its use allows manufacturers to package the product in clear glass or plastic. Without it, opaque or dark packaging would be required.
In biological applications, benzophenones have been used extensively as photophysical probes to identify and map peptide–protein interactions.[2]
Synthesis [edit]
Benzophenone can be prepared by the reaction of benzene with carbon tetrachloride followed by hydrolysis of the resulting diphenyldichloromethane,[3] or by Friedel-Crafts acylation of benzene with benzoyl chloride in the presence of a Lewis acid (e.g. aluminium chloride) catalyst. The industrial synthesis relies on the copper-catalyzed oxidation of diphenylmethane with air.[4]
Organic chemistry [edit]
Benzophenone is a common photosensitizer in photochemistry. It crosses from the S1 state into the triplet state with nearly 100% yield. The resulting diradical will abstract a hydrogen atom from a suitable hydrogen donor to form a ketyl radical.
Benzophenone radical anion [edit]
Sodium reduces benzophenone to the deeply colored radical anion, diphenylketyl:
- Na + Ph2CO → Na+Ph2CO·−
This ketyl is used in the purification of organic solvents, particularly ethers, because it reacts with water and oxygen to give non-volatile products. Very dry solvents are obtained by refluxing over benzophenone and sodium metal prior to distillation.[5][6] The ketyl is soluble in the organic solvent being dried, so it reacts quickly with residual water and oxygen. In comparison, sodium is insoluble, and its heterogeneous reaction is much slower. The ketyl radical generally appears blue or purple, depending on the solvent.
Commercially significant derivatives [edit]
Substituted benzophenones such as oxybenzone and dioxybenzone are used in some sunscreens. The use of benzophenone-derivatives which structurally resemble a strong photosensitizer has been strongly criticized (see sunscreen controversy).[7]
Michler's ketone has dimethylamino substituents at each para position.
The high-strength polymer PEEK is prepared from derivatives of benzophenone.
See also [edit]
References [edit]
- ^ a b c d e f g Merck Index, 11th edition, 1108
- ^ Dorman, Gyorgy; Prestwich, Glenn D. (1 May 1994). "Benzophenone Photophores in Biochemistry". Biochemistry 33 (19): 5661–5673. doi:10.1021/bi00185a001.
- ^ Marvel, C. S.; Sperry, W. M. (1941), "Benzophenone", Org. Synth.; Coll. Vol. 1: 95
- ^ 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
- ^ W. L. F. Armarego and C. Chai (2003). Purification of laboratory chemicals. Oxford: Butterworth-Heinemann. ISBN 0-7506-7571-3.
- ^ L. M. Harwood, C. J. Moody and J. M. Percy (1999). Experimental Organic Chemistry: Standard and Microscale. Oxford: Blackwell Science. ISBN 978-0-632-04819-9.
- ^ Knowland, John; McKenzie, Edward A.; McHugh, Peter J.; Cridland, Nigel A. (1993). "Sunlight-induced mutagenicity of a common sunscreen ingredient". FEBS Letters 324 (3): 309–313. doi:10.1016/0014-5793(93)80141-G. PMID 8405372.
Gallery [edit]
-
A bottle of benzophenone from Lancaster.
-
Toluene is refluxed with sodium and benzophenone to produce dry, oxygen-free toluene.
-
The mixture is still not blue yet indicating that the reaction is not complete.
-
The intense blue coloration due to the benzophenone ketyl radical shows that the toluene is considered free of air and moisture.
-
After the toluene has been thoroughly dried by the sodium and benzophenone, it is distilled at atmospheric pressure under a slight positive pressure of nitrogen to prevent contamination by air into the receiving Schlenk flask.
-
A solvent pot contains dibutyl ether dried over sodium and benzophenone, which gives it its purple color.
