Benzoin (organic compound)
Names | |
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Preferred IUPAC name
2-Hydroxy-1,2-diphenylethan-1-one | |
Other names
2-Hydroxy-2-phenylacetophenone
2-Hydroxy-1,2-diphenylethanone Desyl alcohol Bitter almond oil camphor | |
Identifiers | |
3D model (JSmol)
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3DMet | |
391839 | |
ChEBI | |
ChEMBL | |
ChemSpider | |
ECHA InfoCard | 100.003.938 |
KEGG | |
PubChem CID
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RTECS number |
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
C14H12O2 | |
Molar mass | 212.248 g·mol−1 |
Appearance | Off-white crystals |
Density | 1.310 g/cm3 (20 °C)[1] |
Melting point | 135 to 139[1] °C (275 to 282 °F; 408 to 412 K) |
Boiling point | 330 to 356[1] °C (626 to 673 °F; 603 to 629 K) |
Slightly soluble | |
Solubility in ethanol | Very good[1] |
Solubility in ether | Slightly soluble |
Solubility in chlorine | Soluble |
Solubility in chloroform | Very good[1] |
Hazards | |
GHS labelling: | |
H412 | |
P273, P501 | |
NFPA 704 (fire diamond) | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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10.000 mg/kg |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Benzoin (/ˈbɛnzoʊ.ɪn/ or /-ɔɪn/) 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.
Benzoin is not a constituent of benzoin resin obtained from the benzoin tree (Styrax) or tincture of benzoin. The main component in these natural products is benzoic acid.
History
[edit]Benzoin was first reported in 1832 by Justus von Liebig and Friedrich Woehler during their research on oil of bitter almond, which is benzaldehyde with traces of hydrocyanic acid.[2] The catalytic synthesis by the benzoin condensation was improved by Nikolay Zinin during his time with Liebig.[3][4]
Uses
[edit]The main use of benzoin is as a precursor to benzil, which is used as a photoinitiator.[5][6] The conversion proceeds by organic oxidation using copper(II),[7] nitric acid, or oxone. In one study, this reaction is carried out with atmospheric oxygen and basic alumina in dichloromethane.[8]
Benzoin also sees wide spread use in powder coating formulations, where it acts as a degassing agent during the curing stage. This action prevents surface defects such as 'pinholing'.[9][10]
Benzoin can be used in the preparation of several pharmaceutical drugs including oxaprozin, ditazole, and phenytoin.[11]
Preparation
[edit]Benzoin is prepared from benzaldehyde via the benzoin condensation.[12]
References
[edit]- ^ a b c d e William M. Haynes (2016). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton: CRC Press. p. 3-40. ISBN 978-1-4987-5429-3.
- ^ Wöhler, Liebig; Liebig (1832). "Untersuchungen über das Radikal der Benzoesäure". Annalen der Pharmacie. 3 (3): 249–282. doi:10.1002/jlac.18320030302. hdl:2027/hvd.hxdg3f.
- ^ N. Zinin (1839). "Beiträge zur Kenntniss einiger Verbindungen aus der Benzoylreihe". Annalen der Pharmacie. 31 (3): 329–332. doi:10.1002/jlac.18390310312. Archived from the original on 2022-07-09. Retrieved 2020-09-10.
- ^ N. Zinin (1840). "Ueber einige Zersetzungsprodukte des Bittermandelöls". Annalen der Pharmacie. 34 (2): 186–192. doi:10.1002/jlac.18400340205. Archived from the original on 2022-07-09. Retrieved 2019-06-30.
- ^ Hardo Siegel, Manfred Eggersdorfer "Ketones" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, 2002 by Wiley-VCH, Wienheim. doi:10.1002/14356007.a15_077
- ^ Nakamura, Kenichiro (2015). Photopolymers : photoresist materials, processes, and applications. Boca Raton, FL. ISBN 978-1-4665-1731-8. OCLC 884012539.
{{cite book}}
: CS1 maint: location missing publisher (link) - ^ Clarke, H. T.; Dreger.E. E. (1941). "Benzil". Organic Syntheses; Collected Volumes, vol. 1, p. 87.
- ^ Konstantinos Skobridis; Vassiliki Theodorou; Edwin Weber (2006). "A very simple and chemoselective air oxidation of benzoins to benzils using alumina". Arkivoc. 06-1798JP: 102–106.[permanent dead link]
- ^ Maxwell, B.E; Wilson, R.C; Taylor, H.A; Williams, D.E; Farnham, W; Tria, J (November 2001). "Understanding benzoin's mode of action in powder coatings". Progress in Organic Coatings. 43 (1–3): 158–166. doi:10.1016/S0300-9440(01)00181-3.
- ^ Jahromi, Shahab; Mostert, Ben; Derks, Andreas; Koldijk, Fokelien (December 2003). "Mechanism of action of benzoin as a degassing agent in powder coatings". Progress in Organic Coatings. 48 (2–4): 183–193. doi:10.1016/S0300-9440(03)00096-1.
- ^ U.S. patent 2,242,775
- ^ Roger Adams; C. S. Marvel (1921). "Benzoin". Organic Syntheses. 1: 33; Collected Volumes, vol. 1, 1941, p. 94.
External links
[edit]- Benzoin synthesis, Organic Syntheses, Coll. Vol. 1, p. 94 (1941); Vol. 1, p. 33 (1921)