Phenylglyoxal

Phenylglyoxal

Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name 2-Oxo-2-phenylacetaldehyde
Systematic IUPAC name 2-Oxo-2-phenylethanal
Other names Phenylglyoxal 1-Phenylethanedione
Identifiers
CAS Number	1075-06-5 (monohydrate)^N 1074-12-0 (anhydrous)^Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL233632
ChemSpider	13470^Y
ECHA InfoCard	100.012.761
EC Number	214-036-1
PubChem CID	14090
RTECS number	KM5775180
UNII	N45G3015PA^Y
CompTox Dashboard (EPA)	DTXSID8025888
InChI InChI=1S/C8H6O2/c9-6-8(10)7-4-2-1-3-5-7/h1-6H^N Key: OJUGVDODNPJEEC-UHFFFAOYSA-N^N InChI=1/C8H6O2/c9-6-8(10)7-4-2-1-3-5-7/h1-6H Key: OJUGVDODNPJEEC-UHFFFAOYAA
SMILES O=C(C=O)c1ccccc1
Properties
Chemical formula	C8H6O2
Molar mass	134.13 g/mol (anhydrous)
Appearance	yellow liquid (anhydrous) white crystals (hydrate)
Density	? g/cm^3
Melting point	76 to 79 °C (169 to 174 °F; 349 to 352 K) (hydrate)
Boiling point	63 to 65 °C (145 to 149 °F; 336 to 338 K) (0.5 mmHg, anhydrous)
Solubility in water	forms the hydrate
Solubility in other solvents	common organic solvents
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	toxic
GHS labelling:[1]
Pictograms
Signal word	Warning
Hazard statements	H302, H315, H319, H335
Precautionary statements	P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501
Related compounds
Related aldehydes	3,4-Dihydroxyphenylacetaldehyde Methylglyoxal Phenylacetaldehyde
Related compounds	benzil glyoxal acetophenone
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is ^YN ?) Infobox references

Phenylglyoxal is the organic compound with the formula C₆H₅C(O)C(O)H. It contains both an aldehyde and a ketone functional group. 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, arginine.[2] It has also been used to attach chemical payload (probes) to the amino acid citrulline[3] and to peptides/proteins.[4]

Properties

Like some other aldehydes, phenylglyoxal polymerizes 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 liquid.

Preparation

Phenylglyoxal was first prepared by thermal decomposition of the sulfite derivative of the oxime:[5]

C₆H₅C(O)CH(NOSO₂H) + 2 H₂O → C₆H₅C(O)CHO + NH₄HSO₄

More conveniently, it can be prepared from methyl benzoate by reaction with KCH₂S(O)CH₃ to give PhC(O)CH(SCH₃)(OH), which is oxidized with copper(II) acetate.[6] Alternatively, it can also be prepared by oxidation of acetophenone with selenium dioxide.[7]

References

1. "Phenylglyoxal". pubchem.ncbi.nlm.nih.gov. Retrieved 27 December 2021.
2. Kenji Takahashi (1968). "The Reaction of Phenylglyoxal with Arginine Residues in Proteins". J. Biol. Chem. 243 (23): 6171–9. doi:10.1016/S0021-9258(18)94475-3. PMID 5723461.
3. Bicker KL, Subramanian V, Chumanevich AA, Hofseth LJ, Thompson PR (2012). "Seeing citrulline: development of a phenylglyoxal-based probe to visualize protein citrullination". J Am Chem Soc. 134 (41): 17015–8. doi:10.1021/ja308871v. PMC 3572846. PMID 23030787.
4. Thompson DA, Ng R, Dawson PE (2016). "Arginine selective reagents for ligation to peptides and proteins". J Pept Sci. 22 (5): 311–9. doi:10.1002/psc.2867. PMID 27005702. S2CID 35028264.
5. H. von Pechmann (1887). "Zur Spaltung der Isonitrosoverbindungen". Chem. Ber. 20 (2): 2904–2906. doi:10.1002/cber.188702002156.
6. Mikol, G. J.; Russell, G. A. (1973). "Phenylglyoxal". Organic Syntheses; Collected Volumes, vol. 5, p. 937.
7. Riley, H. A.; Gray, A. R. (1943). "Phenylglyoxal". Organic Syntheses; Collected Volumes, vol. 2, p. 509.