Phenylglyoxal

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Phenylglyoxal
Phenylglyoxal
IUPAC name Phenylglyoxal
Other names 1-phenylethanedione
Identifiers
CAS number [1075-06-5] (monohydrate)
[1074-12-0] (anhydrous)
RTECS number KM5775180
Properties
Molecular formula C8H6O2
Molar mass 134.13 g/mol (anhydrous)
Appearance yellow liquid (anhydrous)
white crystals (hydrate)
Density  ? g/cm3
Melting point

76-79 °C (hydrate)
Boiling point

63–65° (0.5 mm, anhydrous)
Solubility in water forms the hydrate
Solubility in other solvents common organic solvents
Hazards
Main hazards toxic
R-phrases 22-36/37/38
S-phrases 22-26-36
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.

[edit] 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.

[edit] 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]

[edit] References

  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). http://www.orgsyn.org/orgsyn/pdfs/CV2P0509.pdf