Benzophenone

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Benzophenone
Benzophenon.svg
Benzophenone-from-xtal-stable-phase-1968-3D-balls.png
Benzophenone-from-xtal-stable-phase-1968-3D-vdW.png
Benzophenone vial.jpg
Names
Preferred IUPAC name
Diphenylmethanone [1]
Other names
Benzophenone [1]
Phenyl ketone
Diphenyl ketone
Benzoylbenzene
Benzoylphenyl
Identifiers
3D model (JSmol)
1238185
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.003.943 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 204-337-6
4256
KEGG
PubChem CID
RTECS number
  • DI9950000
UNII
UN number 1224
  • InChI=1S/C13H10O/c14-13(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H Yes check.svgY
    Key: RWCCWEUUXYIKHB-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C13H10O/c14-13(11-7-3-1-4-8-11)12-9-5-2-6-10-12/h1-10H
    Key: RWCCWEUUXYIKHB-UHFFFAOYAX
  • O=C(c1ccccc1)c2ccccc2
Properties
C13H10O
Molar mass 182.222 g·mol−1
AppearanceWhite solid
Odor Geranium-like [2]
Density 1.11 g/cm3 [2]
Melting point 48.5 °C (119.3 °F; 321.6 K) [2]
Boiling point 305.4 °C (581.7 °F; 578.5 K) [2]
Insoluble [2]
Solubility in organic solvents 1 g/7.5 mL in ethanol [2]
1 g/6 mL in diethyl ether. [2] Alkanes + tetrachloromethane: better with increasing tetrachloromethane content [3]
-109.6·10−6 cm3/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Harmful (XN)
GHS labelling:
GHS-pictogram-silhouette.svg GHS-pictogram-pollu.svg
Warning
H373, H411
P260, P273, P314, P391, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Flash point 110 °C (230 °F; 383 K)
Safety data sheet (SDS) External MSDS by Sigma-Aldritch
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Benzophenone is a naturally occurring organic compound with the formula (C6H5)2CO, generally abbreviated Ph 2CO. Benzophenone has been found in some fungi, fruits and plants, including grapes. [4] It is a white solid with a low melting point and rose-like odor [5] 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.[ citation needed ]

History

Carl Graebe of the University of Königsberg, in an early literature report from 1874, described working with benzophenone. [5]

Uses

Benzophenone can be used as a photo initiator in ultraviolet (UV)-curing applications [6] such as inks, imaging, and clear coatings in the printing industry. Benzophenone prevents UV light from damaging scents and colors in products such as perfumes and soaps.

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). [7] 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. [8]

Benzophenone is used as an additive in flavorings or perfumes for "sweet-woody-geranium-like notes." [9]

Synthesis

Benzophenone is produced by the copper-catalyzed oxidation of diphenylmethane with air. [10]

A laboratory route involves the reaction of benzene with carbon tetrachloride followed by hydrolysis of the resulting diphenyldichloromethane. [11] 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. [12]

Another route of synthesis is through a palladium(II)/oxometalate catalyst. This converts an alcohol to a ketone with two groups on each side. [13]

Another, less well-known reaction to produce benzophenone is the pyrolysis of anhydrous calcium benzoate. [14]

Organic chemistry

The Haller-Bauer reaction occurs between a non-enolizable ketone and a strong amide base. In this prototypical example involving benzophenone, the tetrahedral intermediate expels phenyl anion to give benzamide and benzene as the organic products. Haller-Bauer reaction.png
The Haller–Bauer reaction occurs between a non-enolizable ketone and a strong amide base. In this prototypical example involving benzophenone, the tetrahedral intermediate expels phenyl anion to give benzamide and benzene as the organic products.

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

Addition of a solution of benzophenone in THF to a vial containing THF, sodium metal, and a stir bar, yielding the deep blue benzophenone anion radical. Playback speed 4x original recording. Notice that the stirbar is not Teflon-coated, which would be attacked by the ketyl.
A solvent pot containing dibutyl ether solution of sodium benzophenone ketyl, which gives it its purple color. Solvent pot.JPG
A solvent pot containing dibutyl ether solution of sodium benzophenone ketyl, which gives it its purple color.

Alkali metals reduce benzophenone to the deeply blue colored radical anion, diphenylketyl: [15]

M + Ph2CO → M+Ph2CO•−

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. [16] [17] Adsorbents such as alumina, silica gel, and especially molecular sieves are superior and far safer. [18] 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. [19] 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: [15]

M + M+Ph2CO•− → (M+)2(Ph2CO)2−

Commercially significant derivatives and analogues

There are over 300 natural benzophenones, with great structural diversity and biological activities. They are being investigated as potential sources of new drugs. [20] Substituted benzophenones such as oxybenzone and dioxybenzone are used in many sunscreens. The use of benzophenone-derivatives which structurally resemble a strong photosensitizer has been criticized (see sunscreen controversy).

Michler's ketone has dimethylamino substituents at each para position. The high-strength polymer PEEK is prepared from derivatives of benzophenone.

2-Amino-5-chlorobenzophenone is used in the synthesis of benzodiazepines. [21]

Safety

It is considered "essentially nontoxic." [10] Benzophenone is however banned as a food additive by the US Food and Drug Administration, despite the FDA's continuing stance that this chemical does not pose a risk to public health under the conditions of its intended use. [22] [23] 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. [24] 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. [25]

Benzophenone is an endocrine disruptor capable of binding to the pregnane X receptor. [26]

Related Research Articles

<span class="mw-page-title-main">Benzoic acid</span> Organic compound (C6H5COOH)

Benzoic acid is a white solid organic compound with the formula C6H5COOH, whose structure consists of a benzene ring with a carboxyl substituent. The benzoyl group is often abbreviated "Bz", thus benzoic acid is also denoted as BzOH, since the benzoyl group has the formula –C6H5CO. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only source.

<span class="mw-page-title-main">Lithium aluminium hydride</span> Chemical compound

Lithium aluminium hydride, commonly abbreviated to LAH, is an inorganic compound with the chemical formula Li[AlH4] or LiAlH4. It is a white solid, discovered by Finholt, Bond and Schlesinger in 1947. This compound is used as a reducing agent in organic synthesis, especially for the reduction of esters, carboxylic acids, and amides. The solid is dangerously reactive toward water, releasing gaseous hydrogen (H2). Some related derivatives have been discussed for hydrogen storage.

<span class="mw-page-title-main">Sodium borohydride</span> Chemical compound

Sodium borohydride, also known as sodium tetrahydridoborate and sodium tetrahydroborate, is an inorganic compound with the formula NaBH4. It is a white crystalline solid, usually encountered as an aqueous basic solution. Sodium borohydride is a reducing agent that finds application in papermaking and dye industries. It is also used as a reagent in organic synthesis.

The Wolff–Kishner reduction is a reaction used in organic chemistry to convert carbonyl functionalities into methylene groups. In the context of complex molecule synthesis, it is most frequently employed to remove a carbonyl group after it has served its synthetic purpose of activating an intermediate in a preceding step. As such, there is no obvious retron for this reaction. The reaction was reported by Nikolai Kischner in 1911 and Ludwig Wolff in 1912.

<span class="mw-page-title-main">Lithium chloride</span> Chemical compound

Lithium chloride is a chemical compound with the formula LiCl. The salt is a typical ionic compound (with certain covalent characteristics), although the small size of the Li+ ion gives rise to properties not seen for other alkali metal chlorides, such as extraordinary solubility in polar solvents (83.05 g/100 mL of water at 20 °C) and its hygroscopic properties.

<span class="mw-page-title-main">Benzoyl chloride</span> Organochlorine compound (C7H5ClO)

Benzoyl chloride, also known as benzenecarbonyl chloride, is an organochlorine compound with the formula C7H5ClO. It is a colourless, fuming liquid with an irritating odour, and consists of a benzene ring with an acyl chloride substituent. It is mainly useful for the production of peroxides but is generally useful in other areas such as in the preparation of dyes, perfumes, pharmaceuticals, and resins.

<span class="mw-page-title-main">Radical anion</span> Free radical species

In organic chemistry, a radical anion is a free radical species that carries a negative charge. Radical anions are encountered in organic chemistry as reduced derivatives of polycyclic aromatic compounds, e.g. sodium naphthenide. An example of a non-carbon radical anion is the superoxide anion, formed by transfer of one electron to an oxygen molecule. Radical anions are typically indicated by .

<span class="mw-page-title-main">Hexamethylphosphoramide</span> Chemical compound

Hexamethylphosphoramide, often abbreviated HMPA, is a phosphoramide (an amide of phosphoric acid) with the formula [(CH3)2N]3PO. This colorless liquid is a useful reagent in organic synthesis.

A pinacol coupling reaction is an organic reaction in which a carbon–carbon bond is formed between the carbonyl groups of an aldehyde or a ketone in presence of an electron donor in a free radical process. The reaction product is a vicinal diol. The reaction is named after pinacol, which is the product of this reaction when done with acetone as reagent. The reaction is usually a homocoupling but intramolecular cross-coupling reactions are also possible. Pinacol was discovered by Wilhelm Rudolph Fittig in 1859.

<span class="mw-page-title-main">Pentacene</span> Hydrocarbon compound (C22H14) made of 5 fused benzene rings

Pentacene is a polycyclic aromatic hydrocarbon consisting of five linearly-fused benzene rings. This highly conjugated compound is an organic semiconductor. The compound generates excitons upon absorption of ultra-violet (UV) or visible light; this makes it very sensitive to oxidation. For this reason, this compound, which is a purple powder, slowly degrades upon exposure to air and light.

<span class="mw-page-title-main">1,4-Benzoquinone</span> Chemical compound

1,4-Benzoquinone, commonly known as para-quinone, is a chemical compound with the formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, and hot plastic or formaldehyde. This six-membered ring compound is the oxidized derivative of 1,4-hydroquinone. The molecule is multifunctional: it exhibits properties of a ketone, being able to form oximes; an oxidant, forming the dihydroxy derivative; and an alkene, undergoing addition reactions, especially those typical for α,β-unsaturated ketones. 1,4-Benzoquinone is sensitive toward both strong mineral acids and alkali, which cause condensation and decomposition of the compound.

<span class="mw-page-title-main">Ketyl</span>

A ketyl group in organic chemistry is an anion radical that contains a group R2C−O•. It is the product of the 1-electron reduction of a ketone.

Barrelene is a bicyclic organic compound with chemical formula C8H8 and systematic name bicyclo[2.2.2]octa-2,5,7-triene. First synthesized and described by Howard Zimmerman in 1960, the name derives from the resemblance to a barrel, with the staves being three ethylene units attached to two methine groups. It is the formal Diels–Alder adduct of benzene and acetylene. Due to its unusual molecular geometry, the compound is of considerable interest to theoretical chemists.

<span class="mw-page-title-main">Rieke metal</span> Group specially prepared, highly reactive metal powder

A Rieke metal is a highly reactive metal powder generated by reduction of a metal salt with an alkali metal. These materials are named after Reuben D. Rieke, who first described along with an associate in 1972 the recipes for their preparation. In 1974 he told about Rieke-magnesium. A 1989 paper by Rieke lists several metals that are allowed by the periodic table to be produced by his process: Cd, Zn, Ni, Pt, Pd, Fe, In, Tl, Co, Cr, Mo, W, Cu, which in turn are called Rieke-nickel, Rieke-platinum, etc.

Air-free techniques refer to a range of manipulations in the chemistry laboratory for the handling of compounds that are air-sensitive. These techniques prevent the compounds from reacting with components of air, usually water and oxygen; less commonly carbon dioxide and nitrogen. A common theme among these techniques is the use of a fine (100–10−3 Torr) or high (10−3–10−6 Torr) vacuum to remove air, and the use of an inert gas: preferably argon, but often nitrogen.

<span class="mw-page-title-main">Chloroauric acid</span> Chemical compound

Chloroauric acid is an inorganic compound with the chemical formula H[AuCl4]. It forms hydrates H[AuCl4]·nH2O. Both the trihydrate and tetrahydrate are known. Both are orange-yellow solids consisting of the planar [AuCl4]− anion. Often chloroauric acid is handled as a solution, such as those obtained by dissolution of gold in aqua regia. These solutions can be converted to other gold complexes or reduced to metallic gold or gold nanoparticles.

In organic chemistry, diazirines are a class of organic molecules consisting of a carbon bound to two nitrogen atoms, which are double-bonded to each other, forming a cyclopropene-like ring, 3H-diazirine. They are isomeric with diazocarbon groups, and like them can serve as precursors for carbenes by loss of a molecule of dinitrogen. For example, irradiation of diazirines with ultraviolet light leads to carbene insertion into various C−H, N−H, and O−H bonds. Hence, diazirines have grown in popularity as small, photo-reactive, crosslinking reagents. They are often used in photoaffinity labeling studies to observe a variety of interactions, including ligand-receptor, ligand-enzyme, protein-protein, and protein-nucleic acid interactions.

<span class="mw-page-title-main">Birch reduction</span> Organic reaction used to convert arenes to cyclohexadienes

The Birch reduction is an organic reaction that is used to convert arenes to 1,4-cyclohexadienes. The reaction is named after the Australian chemist Arthur Birch and involves the organic reduction of aromatic rings in an amine solvent with an alkali metal and a proton source. Unlike catalytic hydrogenation, Birch reduction does not reduce the aromatic ring all the way to a cyclohexane.

<span class="mw-page-title-main">Carbonyl reduction</span> Organic reduction of any carbonyl group by a reducing agent

In organic chemistry, carbonyl reduction is the conversion of any carbonyl group, usually to an alcohol. It is a common transformation that is practiced in many ways. Ketones, aldehydes, carboxylic acids, esters, amides, and acid halides - some of the most pervasive functional groups, -comprise carbonyl compounds. Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with H.

<span class="mw-page-title-main">Phenylsodium</span> Chemical compound

Phenylsodium C6H5Na is an organosodium compound. Solid phenylsodium was first isolated by Nef in 1903. Although the behavior of phenylsodium and phenyl magnesium bromide are similar, the organosodium compound is very rarely used.

References

  1. 1 2 "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. 723–724, 726. doi:10.1039/9781849733069-FP001. ISBN   978-0-85404-182-4.
  2. 1 2 3 4 5 6 7 Merck Index (11th ed.). p. 1108.
  3. ↑ Azizian, Saeid; Haydarpour, Afshin (November 2003). "Solubility of Benzophenone in Binary Alkane + Carbon Tetrachloride Solvent Mixtures". Journal of Chemical & Engineering Data. 48 (6): 1476–1478. doi:10.1021/je0340497.
  4. ↑ Surana, Khemchand; Chaudhary, Bharatkumar; Diwaker, Monika; Sharma, Satyasheel (2018). "Benzophenone: a ubiquitous scaffold in medicinal chemistry". MedChemComm. 9 (11): 1803–1817. doi:10.1039/C8MD00300A. ISSN   2040-2503. PMC   6238883 .
  5. 1 2 "Molecule of the Week Archive: Benzophenone". American Chemical Society. 11 March 2024. Retrieved 20 May 2024.
  6. ↑ 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. Bibcode:2010JCIS..351..556C. doi:10.1016/j.jcis.2010.07.070. PMID   20728089.
  7. ↑ Dornath, Paul John (2010). "Analysis of Chemical Leaching from Common Consumer Plastic Bottles Under High Stress Conditions" (PDF). p. 32. Archived from the original (PDF) on 26 February 2015. Retrieved 26 February 2015.
  8. ↑ Dorman, Gyorgy; Prestwich, Glenn D. (1 May 1994). "Benzophenone Photophores in Biochemistry". Biochemistry. 33 (19): 5661–5673. doi:10.1021/bi00185a001. PMID   8180191.
  9. ↑ Arctander, Steffen. Perfume And Flavor Chemicals: (Aroma Chemicals).
  10. 1 2 Siegel, Hardo; Eggersdorfer, Manfred. "Ketones". Ullmann's Encyclopedia of Industrial Chemistry . Weinheim: Wiley-VCH. doi:10.1002/14356007.a15_077. ISBN   978-3527306732.
  11. ↑ Marvel, C. S.; Sperry, W. M. (1941). "Benzophenone". Organic Syntheses ; Collected Volumes, vol. 1, p. 95.
  12. ↑ "Synthesis of benzoic acid and benzophenone". Journal of the Chemical Society, Abstracts. 34: 69–70. 1878. doi: 10.1039/CA8783400019 .
  13. ↑ Dornan, L.; Muldoon, M. (2015). "A highly efficient palladium(II)/polyoxometalate catalyst system for aerobic oxidation of alcohols". Catalysis Science & Technology. 5 (3): 1428–1432. doi:10.1039/c4cy01632g.
  14. ↑ Lee, C. C. (1953). "The Mechanism of the Ketonic Pyrolysis of Calcium Carboxylates". The Journal of Organic Chemistry. 18 (9): 1079–1086. doi:10.1021/jo50015a003.
  15. 1 2 Connelly, Neil; Geiger, William (28 March 1996). "Chemical Redox Agents for Organometallic Chemistry". Chemical Reviews. 96 (2): 877–910. doi:10.1021/cr940053x. PMID   11848774.
  16. ↑ Armarego, W. L. F.; Chai, C. (2003). Purification of laboratory chemicals. Oxford: Butterworth-Heinemann. ISBN   978-0-7506-7571-0.
  17. ↑ Harwood, L. M.; Moody, C. J.; Percy, J. M. (1999). Experimental Organic Chemistry: Standard and Microscale . Oxford: Blackwell Science. ISBN   978-0-632-04819-9.
  18. ↑ Williams, D. B. G.; Lawton, M. (2010). "Drying of Organic Solvents: Quantitative Evaluation of the Efficiency of Several Desiccants". The Journal of Organic Chemistry. 75 (24): 8351–4. doi:10.1021/jo101589h. PMID   20945830. S2CID   17801540.
  19. ↑ Simas, Alessandro B. C.; Pereira, Vera L. P.; Barreto Jr., Cleber B.; Sales, Daniel L. de; Carvalho, Leandro L. de (2009). "An expeditious and consistent procedure for tetrahydrofuran (THF) drying and deoxygenation by the still apparatus". Química Nova. 32 (9): 2473–2475. doi: 10.1590/S0100-40422009000900042 . ISSN   0100-4042.
  20. ↑ Wu, Shi-Biao; Long, Chunlin; Kennelly, Edward J. (2014). "Structural diversity and bioactivities of natural benzophenones". Nat. Prod. Rep. 31 (9): 1158–1174. doi:10.1039/C4NP00027G. ISSN   0265-0568. PMID   24972079.
  21. ↑ Massah, Ahmad R.; Gharaghani, Sajjad; Lordejani, Hamid Ardeshiri; Asakere, Nahad (1 August 2016). "New and mild method for the synthesis of alprazolam and diazepam and computational study of their binding mode to GABAA receptor". Medicinal Chemistry Research. 25 (8): 1538–1550. doi:10.1007/s00044-016-1585-z. ISSN   1554-8120.
  22. ↑ "FDA Bans Use of 7 Synthetic Food Additives After Environmental Groups Sue". NPR.org. Retrieved 9 October 2018.
  23. ↑ 83 FR 50490
  24. ↑ Consuelo Cuquerella, M.; Lhiaubet-Vallet, V.; Cadet, J.; Miranda, M. A. (2012). "Benzophenone Photosensitized DNA Damage". Acc. Chem. Res. 45 (9): 1558–1570. doi:10.1021/ar300054e. PMID   22698517.
  25. ↑ Doug Brunk (14 March 2014). "Benzophenones named 2014 Contact Allergen of the Year : Dermatology News". Skinandallergynews.com. Archived from the original on 22 March 2016. Retrieved 16 June 2016.
  26. ↑ Mikamo, Eriko; Harada, Shingo; Nishikawa, Jun-Ichi; Nishihara, Tsutomu (2003). "Endocrine disruptors induce cytochrome P450 by affecting transcriptional regulation via pregnane X receptor". Toxicology and Applied Pharmacology. 193 (1): 66–72. doi:10.1016/j.taap.2003.08.001. PMID   14613717.
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