Benzophenone

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Benzophenone
Image:Benzophenone structure.svg
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.

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 desiccants. 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.^[1][1]

Derivatives

• p,p'-bis(N,N-dimethylamino)benzophenone or Michler's ketone has dimethylamino substituents at each para position.

See also

• Desiccant

References

• Merck Index, 11th Edition, 1108.

External links

• External MSDS by JT Baker

Gallery

Benzophenone bottle.jpg A bottle of benzophenone by Lancaster.	Toluene with sodium-benzophenone.jpg Toluene is refluxed with sodium and benzophenone to produce dry, oxygen-free toluene.	Toluene with sodium-benzophenone - brown.jpg The mixture is still not blue yet indicating that the reaction is not complete.	Toluene with sodium-benzophenone - intense blue.jpg The intense blue coloration due to the benzophenone ketyl radical shows that the toluene is considered free of air and moisture.
Distillation of dry and oxygen-free toluene.jpg 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.

lv:Benzofenons

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Acknowledgement and Attribution Regarding Sources of Content

Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .