Phenylglyoxal

Chembox new
Name = Phenylglyoxal
ImageFile = Phenylglyoxal.png ImageName = Phenylglyoxal
IUPACName = Phenylglyoxal
OtherNames = 1-phenylethanedione
Section1 = Chembox Identifiers
SMILES =
CASOther = [1075-06-5] (monohydrate)
[1074-12-0] (anhydrous)
RTECS = KM5775180
Section2 = Chembox Properties
Formula = C₈H₆O₂
MolarMass = 134.13 g/mol (anhydrous)
Appearance = yellow liquid (anhydrous)
white crystals (hydrate)
Density = ? g/cm³
Solubility = forms the hydrate
Solvent = other solvents
SolubleOther = common organic solvents
MeltingPt = 76-79 °C (hydrate)
BoilingPt = 63–65° (0.5 mm, anhydrous)
Section7 = Chembox Hazards
ExternalMSDS =
MainHazards = toxic
FlashPt =
RPhrases = 22-36/37/38
SPhrases = 22-26-36
Section8 = Chembox Related
OtherCpds = benzil
glyoxal
acetophenone

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.

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. [Mikol, G. J.; Russell, G. A. "Phenylglyoxal" Organic Syntheses, Collected Volume 5, p.937 (1973).] Alternatively, it can also be prepared by oxidation of acetophenone with selenium dioxide. [Riley, H. A.; Gray, A. R. "Phenylglyoxal" Organic Syntheses, Collected Volume 2, p.509 (1943). http://www.orgsyn.org/orgsyn/pdfs/CV2P0509.pdf]

References