Benzoin ( or ) is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

with the formula PhCH(OH)C(O)Ph. It is a

hydroxy ketone In organic chemistry a hydroxy ketone (often referred to simply as a ketol) is a functional group consisting of a ketone flanked by a hydroxyl group. In the two main classes, the hydroxyl group can be placed in the alpha position (an alpha-hydroxy ...

attached to two

phenyl In organic chemistry, the phenyl group, or phenyl ring, is a cyclic group of atoms with the formula C6 H5, and is often represented by the symbol Ph. Phenyl group is closely related to benzene and can be viewed as a benzene ring, minus a hydrogen ...

groups. It appears as off-white crystals, with a light

camphor Camphor () is a waxy, colorless solid with a strong aroma. It is classified as a terpenoid and a cyclic ketone. It is found in the wood of the camphor laurel ('' Cinnamomum camphora''), a large evergreen tree found in East Asia; and in the k ...

-like odor. Benzoin is synthesized from

benzaldehyde Benzaldehyde (C6H5CHO) is an organic compound consisting of a benzene ring with a formyl substituent. It is the simplest aromatic aldehyde and one of the most industrially useful. It is a colorless liquid with a characteristic almond-like odor. ...

in the

benzoin condensation The benzoin addition is an addition reaction involving two aldehydes. The reaction generally occurs between aromatic aldehydes or glyoxals, and results in formation of an acyloin. In the classic example, benzaldehyde is converted to benzoin. Th ...

. It is chiral and it exists as a pair of enantiomers: (''R'')-benzoin and (''S'')-benzoin. Benzoin is ''not'' a constituent of

benzoin resin Benzoin or benjamin (corrupted pronunciation) is a balsamic resin obtained from the bark of several species of trees in the genus ''Styrax''. It is used in perfumes and some kinds of incense and as a flavoring and medicine (see tincture of benz ...

obtained from the

benzoin tree ''Styrax'' (common names storax or snowbell) is a genus of about 130 species of large shrubs or small trees in the family Styracaceae, mostly native to warm temperate to tropical regions of the Northern Hemisphere, with the majority in eastern ...

''(Styrax)'' or

tincture of benzoin Tincture of benzoin is a pungent solution of benzoin resin in ethanol. A similar preparation called Friar's Balsam or Compound Benzoin Tincture contains, in addition, Cape aloes or Barbados aloes and storax resin. Friar's balsam was invented by Jo ...

. The main component in these natural products is

benzoic acid Benzoic acid is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, wh ...

History

Benzoin was first reported in 1832 by

Justus von Liebig Justus Freiherr von Liebig (12 May 1803 – 20 April 1873) was a German scientist who made major contributions to agricultural and biological chemistry, and is considered one of the principal founders of organic chemistry. As a professor at t ...

and

Friedrich Woehler Friedrich may refer to: Names * Friedrich (surname), people with the surname ''Friedrich'' * Friedrich (given name), people with the given name ''Friedrich'' Other * Friedrich (board game), a board game about Frederick the Great and the Seven Year ...

during their research on oil of bitter almond, which is

with traces of

hydrocyanic acid Hydrogen cyanide, sometimes called prussic acid, is a chemical compound with the formula HCN and structure . It is a colorless, extremely poisonous, and flammable liquid that boils slightly above room temperature, at . HCN is produced on an ind ...

. The catalytic synthesis by the

was improved by

Nikolay Zinin Nikolay Nikolaevich Zinin (russian: link=no, Никола́й Никола́евич Зи́нин; 25 August 1812, in Shusha – 18 February 1880, in Saint Petersburg) was a Russian organic chemist. Life He studied at the University of Kazan where ...

during his time with Liebig.

Uses

The main uses of benzoin are as a precursor to

benzil 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 photoinitia ...

, which is a

photoinitiator A photoinitiator is a molecule that creates reactive species (free radicals, cations or anions) when exposed to radiation (UV or visible). Synthetic photoinitiators are key components in photopolymers (for example, photo-curable coatings, adhesive ...

.Hardo Siegel, Manfred Eggersdorfer "Ketones" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, 2002 by Wiley-VCH, Wienheim. The conversion proceeds by

organic oxidation Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. In organic chemistry oxidations and reductions are different from ordinary redox reactions, because many reactions carr ...

using copper(II),

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...

, or

oxone Potassium peroxymonosulfate is widely used as an oxidizing agent. It is the potassium salt of peroxymonosulfuric acid. Usually potassium peroxymonosulfate refers to the triple salt known as oxone. The standard electrode potential for potassium p ...

. In one study, this reaction is carried out with atmospheric oxygen and basic alumina in

dichloromethane Dichloromethane (DCM or methylene chloride, methylene bichloride) is an organochlorine compound with the formula . This colorless, volatile liquid with a chloroform-like, sweet odour is widely used as a solvent. Although it is not miscible with ...

. Benzoin can be used in the preparation of several pharmaceutical drugs including

oxaprozin Oxaprozin, also known as oxaprozinum, is a nonsteroidal anti-inflammatory drug (NSAID), used to relieve the inflammation, swelling, stiffness, and joint pain associated with osteoarthritis and rheumatoid arthritis. Chemically, it is a propionic a ...

ditazole Ditazole is a non-steroidal anti-inflammatory agent with analgesic and antipyretic activity similar to phenylbutazone. It is also a platelet aggregation inhibitor which is marketed in Spain and Portugal Portugal, officially the Portuguese R ...

, and

phenytoin Phenytoin (PHT), sold under the brand name Dilantin among others, is an anti-seizure medication. It is useful for the prevention of tonic-clonic seizures (also known as grand mal seizures) and focal seizures, but not absence seizures. The intr ...

Preparation

Benzoin is prepared from

via the

References

External links

Benzoin synthesis
''Organic Syntheses'', Coll. Vol. 1, p. 94 (1941); Vol. 1, p. 33 (1921) {{Authority control Aromatic ketones Acyloins