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Benzophenone is a naturally occurring organic compound with the formula (C6H5)2CO, generally abbreviated phenyl2CO. Benzophenone has been found in some fungi, fruits and plants, including grapes. It is a white solid with a low melting point and rose-like odor that is soluble in organic solvents. Benzophenone is the simplest diaromatic ketone. It is a widely used building block in organic chemistry, being the parent diarylketone.
Benzophenone can also be added to plastic packaging as a UV blocker to prevent photo-degradation of the packaging polymers or its contents. Its use allows manufacturers to package the product in clear glass or plastic (such as a PETE water bottle). 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.
Benzophenone is used as an additive in flavorings or perfumes for "sweet-woody-geranium-like notes".
A laboratory route involves the reaction of benzene with carbon tetrachloride followed by hydrolysis of the resulting diphenyldichloromethane. 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: since benzoyl chloride can itself be produced by the reaction of benzene with phosgene the first synthesis proceeded directly from those materials.
Another route of synthesis is through a palladium(II)/oxometalate catalyst. This converts an alcohol to a ketone with two groups on each side.
Another, less well-known reaction to produce benzophenone is the pyrolysis of anhydrous calcium benzoate.
Generally sodium is used as the alkali metal. Sodium-benzophenone ketyl is used in the purification of organic solvents, particularly ethers, because it reacts with water and oxygen to give non-volatile products. (2025). 9780750675710, Butterworth-Heinemann. ISBN 9780750675710 Adsorbents such as alumina, silica gel, and especially molecular sieves are superior and far safer. The sodium-benzophenone method is common since it gives a visual indication that water, oxygen, and peroxides are absent from the solvent. Large scale purification may be more economical using devices which utilize adsorbents such as the aforementioned alumina or molecular sieves. The ketyl is soluble in the organic solvent being dried, which leads to faster purification. 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:
Substituted benzophenones such as oxybenzone and dioxybenzone are used in . Their use has been criticized (see sunscreen controversy).
Michler's ketone has aniline at each para position.
The high-strength polymer PEEK is generated from 4,4'-difluorobenzophenone. 4,4′-Dihydroxybenzophenone is also interest in this context.David Parker, Jan Bussink, Hendrik T. van de Grampe, Gary W. Wheatley, Ernst-Ulrich Dorf, Edgar Ostlinning, Klaus Reinking "Polymers, High-Temperature" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. 4-Chloro-4'-hydroxybenzophenone is used to make related . (2025). 9783527306732 ISBN 9783527306732
The European Union permits it as a flavouring substance, having established a Total Dietary Intake of 0.3mg/kg of body weight per day.
Benzophenone derivatives are known to be pharmacologically active. From a molecular chemistry point of view interaction of benzophenone with B-DNA has been demonstrated experimentally. The interaction with DNA and the successive photo-induced energy transfer is at the base of the benzophenone activity as a DNA photosensitizer and may explain part of its therapeutic potentialities.
In 2014, benzophenones were named Contact Allergen of the Year by the American Contact Dermatitis Society.
Benzophenone is an endocrine disruptor capable of binding to the pregnane X receptor.
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