Benzophenone

From Wikipedia, the free encyclopedia
Jump to: navigation, search
This article is about the basic chemical. For benzophenone-1 – benzophenone-12, see benzophenone-n.
Benzophenone
Benzophenon.svg
Benzophenone-3D-vdW.png
Benzophenone-3D-balls.png
Identifiers
CAS number 119-61-9 YesY
PubChem 3102
ChemSpider 2991 YesY
UNII 701M4TTV9O YesY
DrugBank DB01878
KEGG C06354 YesY
ChEBI CHEBI:41308 YesY
ChEMBL CHEMBL90039 YesY
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 (119.3 °F; 321.6 K)[1]
Boiling point 305.4 °C (581.7 °F; 578.5 K)[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
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 110 °C (230 °F; 383 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
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.

Uses[edit]

Benzophenone can be used as a photo initiator in UV-curing applications[2] 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.[3]

Synthesis[edit]

Benzophenone is produced by the copper-catalyzed oxidation of diphenylmethane with air.[4]

A laboratory route involves the reaction of benzene with carbon tetrachloride followed by hydrolysis of the resulting diphenyldichloromethane.[5] It can also be prepared by Friedel-Crafts acylation of benzene with benzoyl chloride in the presence of a Lewis acid (e.g. aluminium chloride) catalyst.

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]

Main article: Air-free technique

Alkali metals reduce benzophenone to the deeply blue colored radical anion, diphenylketyl:[6]

M + Ph2CO → M+Ph2CO·−

Generally sodium is used as the alkali metal. Although inferior in terms of safety and effectiveness relative to molecular sieves,[7] this ketyl is used in the purification of organic solvents, particularly ethers, because it reacts with water and oxygen to give non-volatile products.[8][9] The ketyl is soluble in the organic solvent being dried, so it accelerates the reaction of the sodium with water and oxygen. In comparison, sodium is insoluble, and its heterogeneous reaction is much slower. When excess alkali metal is present a second reduction may occur, resulting in a color transformation from deep blue to purple:[6]

M + M+Ph2CO·− → (M+)2(Ph2CO)2-

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).[10]

Michler's ketone has dimethylamino substituents at each para position.

The high-strength polymer PEEK is prepared from derivatives of benzophenone.

Pharmacological activity[edit]

Benzophenone derivatives are known to be pharmacologically active. From a molecular chemistry point of view interaction of benzophenone with B-DNA has been clearly demonstrated both experimentally [11]The interaction with DNA and the successive photo-induced energy transfer is at the base of the benzophenone activity as a DNA photosensitizers and may explain part of its therapeutic potentialities.

In 2014, benzophenones were named Contact Allergen of the Year by the American Contact Dermatitis Society.[12]

References[edit]

  1. ^ a b c d e f g Merck Index, 11th edition, 1108
  2. ^ Carroll, G.T.; Turro, N.J.; Koberstein, J.T. (2010). "Patterning dewetting in thin polymer films by spatially directed photocrosslinking". Journal of Colloid and Interface Science 351 (2): 556–560. doi:10.1016/j.jcis.2010.07.070. 
  3. ^ Dorman, Gyorgy; Prestwich, Glenn D. (1 May 1994). "Benzophenone Photophores in Biochemistry". Biochemistry 33 (19): 5661–5673. doi:10.1021/bi00185a001. 
  4. ^ 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
  5. ^ Marvel, C. S.; Sperry, W. M. (1941), Benzophenone, Org. Synth. ; Coll. Vol. 1: 95 
  6. ^ a b Connelly, Neil; Geiger, William (March 28, 1996). "Chemical Redox Agents for Organometallic Chemistry". Chemical Reviews. doi:10.1021/cr940053x. Retrieved May 14, 2014. 
  7. ^ Williams, D. B. G., Lawton, M., "Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants", The Journal of Organic Chemistry 2010, vol. 75, 8351. doi: 10.1021/jo101589h
  8. ^ W. L. F. Armarego and C. Chai (2003). Purification of laboratory chemicals. Oxford: Butterworth-Heinemann. ISBN 0-7506-7571-3. 
  9. ^ 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. 
  10. ^ 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. 
  11. ^ Consuelo Cuquerella, M.; Lhiaubet-Vallet, V.; Cadet, J.; Miranda, M. A. (2012). "Benzophenone Photosensitized DNA Damage". Acc. Chem. Res. 45: 1558–1570. doi:10.1021/ar300054e. 
  12. ^ http://www.skinandallergynews.com/single-view/benzophenones-named-2014-contact-allergen-of-the-year/cb086f7e351cccbcfd9dbf5fa806762b.html

Gallery[edit]