Pyrazine

Pyrazine
IUPAC name

Pyrazine
Other names

1,4-Diazabenzene, p-Diazine, 1,4-Diazine, Paradiazine, Piazine, UN 1325
Identifiers
CAS number 290-37-9 Y
PubChem 9261
ChemSpider 8904 Y
EC number 206-027-6
ChEBI CHEBI:30953 Y
ChEMBL CHEMBL15797 Y
Jmol-3D images Image 1
Properties
Molecular formula C4H4N2
Molar mass 80.09 g/mol
Appearance White crystals
Density 1.031 g/cm3
Melting point

52 °C, 325 K, 126 °F
Boiling point

115 °C, 388 K, 239 °F
Solubility in water Soluble
Acidity (pKa) 0.37[1] (protonated pyrazine)
Hazards
R-phrases R11, R36/37/38
S-phrases S16, S26, S36
NFPA 704
2
2
0
Flash point 55 °C c.c.
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Pyrazine is a heterocyclic aromatic organic compound with the chemical formula C4H4N2.

Pyrazine is a symmetrical molecule with point group D2h. Derivatives like phenazine are well known for their antitumor, antibiotic and diuretic activity. Pyrazine is less basic in nature than pyridine, pyridazine and pyrimidine. Tetramethylpyrazine (also known as ligustrazine) is reported to scavenge superoxide anion and decrease nitric oxide production in human polymorphonuclear leukocytes[2]. Tetramethylpyrazine is also a component of some herbs in traditional Chinese medicine[3].

Contents

Synthesis

Many methods exist for the organic synthesis of pyrazine and derivatives and some of them very old.

In the Staedel-Rugheimer pyrazine synthesis (1876) 2-chloroacetophenone is reacted with ammonia to the amino ketone, then condensed and then oxidized to a pyrazine [4] A variation is the Gutknecht pyrazine synthesis (1879) also based on this selfcondensation but differing in the way the alpha-ketoamine is synthesised (the chlorine compound in the above method is a lachrymatory agent) [5] [6]

The Gastaldi synthesis (1921) is another variation [7] [8]:

See also

External links

References

  1. ^ Brown, H.C., et al., in Baude, E.A. and Nachod, F.C., Determination of Organic Structures by Physical Methods, Academic Press, New York, 1955.
  2. ^ Life Sciences, 2003, 72, 2465-2472, DOI: http://dx.doi.org/10.1016/S0024-3205(03)00139-5
  3. ^ http://www.itmonline.org/arts/ligustrazine.htm
  4. ^ Ueber die Einwirkung von Ammoniak auf Chloracetylbenzol (p 563-564) W. Staedel, L. Rügheimer doi:10.1002/cber.187600901174 Berichte der deutschen chemischen Gesellschaft Volume 9, Issue 1 , Pages 563 - 564 1876
  5. ^ Mittheilungen Ueber Nitrosoäthylmethylketon H. Gutknecht Berichte der deutschen chemischen Gesellschaft Volume 12, Issue 2 , Pages 2290 - 2292 1879 doi:10.1002/cber.187901202284
  6. ^ Heterocyclic chemistry T.L. Gilchrist ISBN 0-582-01421-2
  7. ^ G. Gastaldi, Gazz. Chim. Ital. 51, (1921) 233
  8. ^ Amines: Synthesis, Properties and Applications Stephen A. Lawrence 2004 Cambridge University Press ISBN 0521782848