Phenylglyoxal

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Phenylglyoxal
Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name
Oxo(phenyl)acetaldehyde
Other names
Phenylglyoxal
1-Phenylethanedione
Identifiers
3D model (Jmol)
ChemSpider
ECHA InfoCard 100.012.761
RTECS number KM5775180
UNII
Properties
C8H6O2
Molar mass 134.13 g/mol (anhydrous)
Appearance yellow liquid (anhydrous)
white crystals (hydrate)
Density  ? g/cm3
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)
forms the hydrate
Solubility in other solvents common organic solvents
Hazards
Main hazards toxic
R-phrases (outdated) 22-36/37/38
S-phrases (outdated) 22-26-36
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).
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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.[1]

Properties[edit]

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[edit]

Phenylglyoxal was first prepared by thermal decomposition of the sulfite derivative of the oxime:[2]

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.[3] Alternatively, it can also be prepared by oxidation of acetophenone with selenium dioxide.[4]

References[edit]

  1. ^ Kenji Takahashi (1968). "The Reaction of Phenylglyoxal with Arginine Residues in Proteins". J. Biol. Chem. 243 (23): 6171–9. PMID 5723461. 
  2. ^ H. von Pechmann (1887). "Zur Spaltung der Isonitrosoverbindungen". Chem. Ber. 20 (2): 2904–2906. doi:10.1002/cber.188702002156. 
  3. ^ Mikol, G. J.; Russell, G. A. (1973). "Phenylglyoxal". Org. Synth. ; Coll. Vol., 5, p. 937 
  4. ^ Riley, H. A.; Gray, A. R. (1943). "Phenylglyoxal". Org. Synth. ; Coll. Vol., 2, p. 509