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Systematic name Phenylglyoxal
Other names 1-phenylethanedione
Molecular formula C8H6O2
Molar mass 134.13 g/mol (anhydrous)
Appearance yellow liquid (anhydrous)
white crystals (hydrate)
CAS number [1075-06-5] (monohydrate)
[1074-12-0] (anhydrous)
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)
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
n, εr, etc.
Phase behaviour
Solid, liquid
Spectral data UV, IR, NMR, MS
Related compounds
Related compounds benzil
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.


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.


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]


  1. ^ Mikol, G. J.; Russell, G. A. "Phenylglyoxal" Organic Syntheses, Collected Volume 5, p.937 (1973).
  2. ^ Riley, H. A.; Gray, A. R. "Phenylglyoxal" Organic Syntheses, Collected Volume 2, p.509 (1943).
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Phenylglyoxal". A list of authors is available in Wikipedia.
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