Phenylglyoxal is the

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 In science, a formula is a concise way of expressing information symbolically, as in a mathematical formula or a ''chemical formula''. The informal use of the term ''formula'' in science refers to the general construct of a relationship betwee ...

C₆H₅C(O)C(O)H. It contains both an

aldehyde In organic chemistry, an aldehyde () is an organic compound containing a functional group with the structure . The functional group itself (without the "R" side chain) can be referred to as an aldehyde but can also be classified as a formyl grou ...

and a

ketone In organic chemistry, a ketone is a functional group with the structure R–C(=O)–R', where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group –C(=O)– (which contains a carbon-oxygen double bo ...

functional group In organic chemistry, a functional group is a substituent or moiety in a molecule that causes the molecule's characteristic chemical reactions. The same functional group will undergo the same or similar chemical reactions regardless of the rest ...

. It is yellow liquid when anhydrous but readily forms a colorless crystalline hydrate. It has been used as a reagent to modify the

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha am ...

arginine Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) and both the am ...

. It has also been used to attach chemical payload (probes) to the amino acid citrulline and to peptides/proteins.

Properties

Like some other aldehydes, phenylglyoxal

polymerizes In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many for ...

upon standing, as indicated by solidification of the liquid. Upon heating, this polymer "cracks" to give back the yellow aldehyde. Dissolution of phenylglyoxal in water gives crystals of the hydrate: : C₆H₅C(O)COH + H₂O → C₆H₅C(O)CH(OH)₂ Upon heating, the hydrate loses water and regenerates the

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achie ...

liquid.

Preparation

Phenylglyoxal was first prepared by thermal decomposition of the

sulfite Sulfites or sulphites are compounds that contain the sulfite ion (or the sulfate(IV) ion, from its correct systematic name), . The sulfite ion is the conjugate base of bisulfite. Although its acid ( sulfurous acid) is elusive, its salts are wide ...

derivative of the

oxime In organic chemistry, an oxime is a organic compound belonging to the imines, with the general formula , where R is an organic side-chain and R’ may be hydrogen, forming an aldoxime, or another organic group, forming a ketoxime. O-substituted ...

: : C₆H₅C(O)CH(NOSO₂H) + 2 H₂O → C₆H₅C(O)CHO + NH₄HSO₄ More conveniently, it can be prepared from

methyl benzoate Methyl benzoate is an organic compound. It is an ester with the chemical formula C6H5CO2CH3. It is a colorless liquid that is poorly soluble in water, but miscible with organic solvents. Methyl benzoate has a pleasant smell, strongly reminiscen ...

by reaction with KCH₂S(O)CH₃ to give PhC(O)CH(SCH₃)(OH), which is oxidized with

copper(II) acetate Copper(II) acetate, also referred to as cupric acetate, is the chemical compound with the formula Cu(OAc)2 where AcO− is acetate (). The hydrated derivative, Cu2(OAc)4(H2O)2, which contains one molecule of water for each copper atom, is availab ...

. Alternatively, it can also be prepared by oxidation of

acetophenone Acetophenone is the organic compound with the formula C6H5C(O)CH3. It is the simplest aromatic ketone. This colorless, viscous liquid is a precursor to useful resins and fragrances. Production Acetophenone is formed as a byproduct of the cumene p ...

with

selenium dioxide Selenium dioxide is the chemical compound with the formula SeO2. This colorless solid is one of the most frequently encountered compounds of selenium. Properties Solid SeO2 is a one-dimensional polymer, the chain consisting of alternating seleniu ...

References

{{Reflist Aldehydes Aromatic ketones Phenyl compounds