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Phenylglyoxal

Phenylglyoxal

General
Systematic name	Phenylglyoxal
Other names	1-phenylethanedione
Molecular formula	C₈H₆O₂
SMILES	?
Molar mass	134.13 g/mol (anhydrous)
Appearance	yellow liquid (anhydrous) white crystals (hydrate)
CAS number	[1075-06-5] (monohydrate) [1074-12-0] (anhydrous)
Properties
Density and phase	? g/cm³
Solubility in water	forms the hydrate
Other solvents	common organic solvents
Melting point	76-79 °C (hydrate)
Boiling point	63–65° (0.5 mm, anhydrous)
Hazards
MSDS	External MSDS
Main hazards	toxic
NFPA 704
Flash point	? °C
R/S statement	R: 22-36/37/38 S: 22-26-36
RTECS number	KM5775180
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid
Spectral data	UV, IR, NMR, MS
Related compounds
Related compounds	benzil glyoxal acetophenone
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Phenylglyoxal is the chemical compound with the formula C₆H₅C(O)C(O)H. It contains both an aldehyde and a ketone functional groups. 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.

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Properties

This aldehyde has interesting behavior that illustrate some properties of aldehydes. The yellow liquid solidifes with time, apparently due to oligomerization. Upon heating, this polymer "cracks" to give back the yellow liquid. Dissolution of phenylglyoxal in water gives crystals of the hydrate, C₆H₅C(O)CH(OH)₂. Again by distillation, the anhydrous material is regenerated.

Preparation

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.^[1] Alternatively, it can also be prepared by oxidation of acetophenone with selenium dioxide.^[2]

References

^ Mikol, G. J.; Russell, G. A. "Phenylglyoxal" Organic Syntheses, Collected Volume 5, p.937 (1973).
^ Riley, H. A.; Gray, A. R. "Phenylglyoxal" Organic Syntheses, Collected Volume 2, p.509 (1943). http://www.orgsyn.org/orgsyn/pdfs/CV2P0509.pdf

Categories: Aldehydes | Ketones