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Benzophenone



Benzophenone
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 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
Main hazards Harmful (XN)
NFPA 704
1
1
0
 
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. Substituted benzophenones such as oxybenzone and dioxybenzone are used in sunscreen.

Additional recommended knowledge

Contents

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. This allows manufacturers to package the product in clear glass or plastic. Without it, opaque or dark packaging would be used.

In laboratories, solvents are often distilled with sodium and benzophenone as desicants. The product of these two chemicals in the absence of air and water is a dark blue ketyl; a solution of this ketyl can be used to qualitatively test for the absence of air and water.

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. aluminum chloride) catalyst.

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.

Benzophenone radical anion

Sodium is commonly used as a desiccant to purify solvents by reacting with water to give the hydroxide, which is nonvolatile:

Na + H2O → NaOH + 1/2 H2

The main problem with the use of sodium as a desiccant (below its melting point) is associated with the slow rate of reaction between a solid and a solution. When however, the desiccant is soluble, the speed of drying is much higher. Benzophenone is often used to generate such a soluble drying agent. An advantage to this application is the intense blue color of the ketyl radical anion. Thus, sodium/benzophenone can be used as an indicator of air-free and moisture-free conditions in the purification of solvents by distillation.[2][3]

Derivatives

See also

References

  • Merck Index, 11th Edition, 1108.
  1. ^ Marvel, C. S.; Sperry, W. M. (1941). "Benzophenone". Org. Synth.; Coll. Vol. 1: 95. 
  2. ^ Nathan L. Bauld (2001). Unit 6: Anion Radicals. University of Texas.
  3. ^ W. L. F. Armarego and C. Chai (2003). Purification of laboratory chemicals. Butterworth-Heinemann. ISBN 0750675713. 

Gallery

 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Benzophenone". A list of authors is available in Wikipedia.
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