Benzophenone
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Benzophenone | |
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IUPAC name | Benzophenone |
Other names | Diphenylmethanone; phenyl ketone; diphenyl ketone; benzoylbenzene |
Identifiers | |
CAS number | [119-61-9] |
SMILES | O=C(C2=CC=CC=C2)C1=CC=CC=C1 |
InChI | 1/C13H10O/c14-13(11-7-3-1-4-8-11) 12-9-5-2-6-10-12/h1-10H |
Properties | |
Molecular formula | C13H10O |
Molar mass | 182.217 g/mol |
Appearance | White solid |
Density | 1.11 g/cm3, solid |
Melting point |
47.9 °C |
Boiling point |
305.4 °C |
Solubility in water | insoluble |
Solubility | benzene, THF, ethanol, propylene glycol |
Hazards | |
MSDS | External MSDS by JT Baker |
Main hazards | Harmful (XN) |
NFPA 704 | |
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and 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 |
[edit] Uses
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.
[edit] Synthesis
Benzophenone can be prepared by the reaction of benzene with carbon tetrachloride followed by hydrolysis of the resulting diphenyldichloromethane,[1] 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.[2]
[edit] Organic chemistry
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.
[edit] Benzophenone radical anion
Sodium reduces benzophenone to the deeply colored radical anion, diphenylketyl:
- Na + Ph2CO → Na+Ph2CO−
This ketyl is used in the purification of hydrocarbon solvents, because it reacts with water and oxygen to give colorless non-volatile products:[3]
- Na + H2O → NaOH + ½H2
[edit] Commercially significant derivatives
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 critisized.[4] (see sunscreen controversy)
p,p'-bis(N,N-dimethylamino)benzophenone or Michler's ketone has dimethylamino substituents at each para position.
The high-strength polymers PEEK, polyetherether ketones, are prepared from derivatives of benzophenone.
[edit] References
- Merck Index, 11th Edition, 1108.
- ^ 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. Butterworth-Heinemann. ISBN 0750675713.
- ^ 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.
[edit] Gallery
Toluene is refluxed with sodium and benzophenone to produce dry, oxygen-free toluene. |
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