Benzil

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Benzil
Benzil.svg
Benzil-from-LT-monoclinic-xtal-CM-3D-balls.png
Benzil-from-LT-monoclinic-xtal-CM-3D-SF.png
Names
Preferred IUPAC name
Diphenylethanedione
Systematic IUPAC name
1,2-Diphenylethane-1,2-dione
Other names
Diphenylethane-1,2-dione
Benzil
Dibenzoyl
Bibenzoyl
Diphenylglyoxal
Identifiers
3D model (JSmol)
608047
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.689 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 205-157-0
PubChem CID
RTECS number
  • DD1925000
UNII
  • InChI=1S/C14H10O2/c15-13(11-7-3-1-4-8-11)14(16)12-9-5-2-6-10-12/h1-10H Yes check.svgY
    Key: WURBFLDFSFBTLW-UHFFFAOYSA-N Yes check.svgY
  • InChI=1/C14H10O2/c15-13(11-7-3-1-4-8-11)14(16)12-9-5-2-6-10-12/h1-10H
    Key: WURBFLDFSFBTLW-UHFFFAOYAZ
  • O=C(C(=O)c1ccccc1)c2ccccc2
  • c1ccccc1C(=O)C(=O)c2ccccc2
Properties
C14H10O2
Molar mass 210.232 g·mol−1
Appearanceyellow crystalline powder
Density 1.23 g/cm3, solid (1.255 g/cm3, x-ray)
Melting point 94.0 to 96.0 °C; 201.2 to 204.8 °F; 367.1 to 369.2 K
Boiling point 346.0 to 348.0 °C; 654.8 to 658.4 °F; 619.1 to 621.1 K
insoluble
Solubility in ethanol soluble
Solubility in diethyl ether soluble
Solubility in benzene soluble
-118.6·10−6 cm3/mol
Structure
P31,221 [1]
3.8 D [2]
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Irritant
GHS labelling:
GHS-pictogram-exclam.svg
Warning
H315, H319, H335
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704.svgHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 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
2
1
0
Lethal dose or concentration (LD, LC):
>3 g/kg (mouse, oral) [3]
Related compounds
Related diketones
diacetyl
Related compounds
benzophenone
glyoxal
bibenzil
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 ?)

Benzil (i.e. Bz2, systematically known as 1,2-diphenylethane-1,2-dione) is the organic compound with the formula (C6H5 CO)2, generally abbreviated (PhCO)2. This yellow solid is one of the most common diketones. Its main use is as a photoinitiator in polymer chemistry. [4]

Contents

Structure

The compound's most noteworthy structural feature is the long carbon-carbon bond of 1.54 Å, which indicates the absence of pi-bonding between the two carbonyl centers. The PhCO centers are planar, but the pair of benzoyl groups are twisted with respect to the other with a dihedral angle of 117°. [5] In less hindered analogues (glyoxal, biacetyl, oxalic acid derivatives), the (RCO)2 group adopts a planar, anti-conformation.

Applications

Most benzil can be used as a photoinitiator in the free-radical curing of polymer networks. It absorbs ultraviolet radiation at a wavelength of 260 nm, leading to decomposition with formation of free-radical species and formation of cross-links within the material. However, it is a relatively poor photoinitiator, and is seldom used. It undergoes photobleaching, which allows the curing light to reach deeper layers of the material on longer exposure. [6] Acetal derivatives, such as 2,2-dimethoxy-2-phenylacetophenone, have better properties for this application. [6]

Benzil is a potent inhibitor of human carboxylesterases, enzymes involved in the hydrolysis of carboxylesters and many clinically used drugs. [7]

Reactions

Benzil is a standard building block in organic synthesis. It condenses with amines to give diketimine ligands. A classic organic reaction of benzil is the benzilic acid rearrangement, in which base catalyses the conversion of benzil to benzilic acid. This reactivity is exploited in the preparation of the drug phenytoin. Benzil also reacts with 1,3-diphenylacetone in an aldol condensation to give tetraphenylcyclopentadienone.

Preparation

Benzil is prepared from benzoin, for example with copper(II) acetate: [8]

PhC(O)CH(OH)Ph + 2 Cu2+ → PhC(O)C(O)Ph + 2 H+ + 2 Cu+

Other suitable oxidizing agents such as nitric acid (HNO3) are used routinely.

Iron(III) chloride (FeCl3) can be used as an inexpensive catalyst for this chemical conversion. [9]

Related Research Articles

<span class="mw-page-title-main">Ester</span> Compound derived from an acid

In chemistry, an ester is a compound derived from an acid in which the hydrogen atom (H) of at least one acidic hydroxyl group of that acid is replaced by an organyl group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well, but not according to the IUPAC.

<span class="mw-page-title-main">Dicarbonyl</span> Molecule containing two adjacent C=O groups

In organic chemistry, a dicarbonyl is a molecule containing two carbonyl groups. Although this term could refer to any organic compound containing two carbonyl groups, it is used more specifically to describe molecules in which both carbonyls are in close enough proximity that their reactivity is changed, such as 1,2-, 1,3-, and 1,4-dicarbonyls. Their properties often differ from those of monocarbonyls, and so they are usually considered functional groups of their own. These compounds can have symmetrical or unsymmetrical substituents on each carbonyl, and may also be functionally symmetrical or unsymmetrical.

Cyclohexene is a hydrocarbon with the formula (CH2)4C2H2. It is a colorless liquid with a sharp odor. Although it is one of the simplest cycloalkene, it has few applications.

<span class="mw-page-title-main">Organotin chemistry</span> Branch of organic chemistry

Organotin chemistry is the scientific study of the synthesis and properties of organotin compounds or stannanes, which are organometallic compounds containing tin–carbon bonds. The first organotin compound was diethyltin diiodide, discovered by Edward Frankland in 1849. The area grew rapidly in the 1900s, especially after the discovery of the Grignard reagents, which are useful for producing Sn–C bonds. The area remains rich with many applications in industry and continuing activity in the research laboratory.

<span class="mw-page-title-main">Benzoin (organic compound)</span> Chemical compound

Benzoin ( or ) is an organic compound with the formula PhCH(OH)C(O)Ph. It is a hydroxy ketone attached to two phenyl groups. It appears as off-white crystals, with a light camphor-like odor. Benzoin is synthesized from benzaldehyde in the benzoin condensation. It is chiral and it exists as a pair of enantiomers: (R)-benzoin and (S)-benzoin.

<span class="mw-page-title-main">Sulfoxide</span> Organic compound containing a sulfinyl group (>SO)

In organic chemistry, a sulfoxide, also called a sulphoxide, is an organosulfur compound containing a sulfinyl functional group attached to two carbon atoms. It is a polar functional group. Sulfoxides are oxidized derivatives of sulfides. Examples of important sulfoxides are alliin, a precursor to the compound that gives freshly crushed garlic its aroma, and dimethyl sulfoxide (DMSO), a common solvent.

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

1,3,5,7-Cyclooctatetraene (COT) is an unsaturated derivative of cyclooctane, with the formula C8H8. It is also known as [8]annulene. This polyunsaturated hydrocarbon is a colorless to light yellow flammable liquid at room temperature. Because of its stoichiometric relationship to benzene, COT has been the subject of much research and some controversy.

(<i>E</i>)-Stilbene Chemical compound

(E)-Stilbene, commonly known as trans-stilbene, is an organic compound represented by the condensed structural formula C6H5CH=CHC6H5. Classified as a diarylethene, it features a central ethylene moiety with one phenyl group substituent on each end of the carbon–carbon double bond. It has an (E) stereochemistry, meaning that the phenyl groups are located on opposite sides of the double bond, the opposite of its geometric isomer, cis-stilbene. Trans-stilbene occurs as a white crystalline solid at room temperature and is highly soluble in organic solvents. It can be converted to cis-stilbene photochemically, and further reacted to produce phenanthrene.

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

A quinoxaline, also called a benzopyrazine, in organic chemistry, is a heterocyclic compound containing a ring complex made up of a benzene ring and a pyrazine ring. It is isomeric with other naphthyridines including quinazoline, phthalazine and cinnoline. It is a colorless oil that melts just above room temperature. Although quinoxaline itself is mainly of academic interest, quinoxaline derivatives are used as dyes, pharmaceuticals, and antibiotics such as olaquindox, carbadox, echinomycin, levomycin and actinoleutin.

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

Fluorene, or 9H-fluorene is an organic compound with the formula (C6H4)2CH2. It forms white crystals that exhibit a characteristic, aromatic odor similar to that of naphthalene. It has a violet fluorescence, hence its name. For commercial purposes it is obtained from coal tar. It is insoluble in water and soluble in many organic solvents. Although sometimes classified as a polycyclic aromatic hydrocarbon, the five-membered ring has no aromatic properties. Fluorene is mildly acidic.

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The Gabriel–Colman rearrangement is the chemical reaction of a saccharin or phthalimido ester with a strong base, such as an alkoxide, to form substituted isoquinolines. First described in 1900 by chemists Siegmund Gabriel and James Colman, this rearrangement, a ring expansion, is seen to be general if there is an enolizable hydrogen on the group attached to the nitrogen, since it is necessary for the nitrogen to abstract a hydrogen to form the carbanion that will close the ring. As shown in the case of the general example below, X is either CO or SO2.

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

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References

  1. Acta Crystallogr. B43 398 (1987)
  2. Spectrochim. Acta A60 (8-9) 1805 (2004)
  3. "Benzil".
  4. Hardo Siegel, Manfred Eggersdorfer "Ketones" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, 2002 by Wiley-VCH, Weinheim. doi : 10.1002/14356007.a15_077
  5. Quang. Shen, Kolbjoern. Hagen "Gas-phase molecular structure and conformation of benzil as determined by electron diffraction" J. Phys. Chem., 1987, 91 (6), pp 1357–1360. doi : 10.1021/j100290a017.
  6. 1 2 Green, W. Arthur (2010-04-22). Industrial Photoinitiators: A Technical Guide. p. 31. ISBN   9781439827468 . Retrieved 2022-05-21.
  7. Wadkins. R. M. et al "Identification and characterization of novel benzil (diphenylethane-1,2-dione) analogues as inhibitors of mammalian carboxylesterases. J. Med. Chem., 2005 48 pp 2906–15.
  8. Depreux, P.; Bethegnies, G.; Marcincal-Lefebvre, A. (1988). "Synthesis of benzil from benzoin with copper(II) acetate". Journal of Chemical Education. 65 (6): 553. Bibcode:1988JChEd..65..553D. doi:10.1021/ed065p553.
  9. Bi, Xiaoxin; Wu, Lintao; Yan, Chaoguo; Jing, Xiaobi; Zhu, Hongxiang (2011). "One-Pot Synthesis Benzils from Aldehydes Via Nhc-Catalyzed Benzoin Dimerization Under Metal-Free Conditions in Water". Journal of the Chilean Chemical Society. 56 (2): 663. doi: 10.4067/S0717-97072011000200008 .