Quinoxaline

Quinoxaline

Skeletal formula of quinoxaline
C=black, H=white, N=blue C=black, H=white, N=blue
Names
Preferred IUPAC name Quinoxaline [1]
Other names Benzo[b]pyrazine, Benzopyrazine, Benzoparadiazine, 1,4-Benzodiazine, Phenopiazine, Phenpiazine, Quinazine, Chinoxalin
Identifiers
CAS Number	91-19-0  Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:36616  Y
ChEMBL	ChEMBL39444  Y
ChemSpider	21106470  Y
ECHA InfoCard	100.001.862
EC Number	202-047-4
KEGG	C18575  Y
PubChem CID	7045
UNII	QM4AR6M6T8  Y
CompTox Dashboard (EPA)	DTXSID6049432
InChI InChI=1S/C8H6N2/c1-2-4-8-7(3-1)9-5-6-10-8/h1-6H Y Key: XSCHRSMBECNVNS-UHFFFAOYSA-N Y InChI=1/C8H6N2/c1-2-4-8-7(3-1)9-5-6-10-8/h1-6H Key: XSCHRSMBECNVNS-UHFFFAOYAS
SMILES c1cccc2nccnc12
Properties
Chemical formula	C8H6N2
Molar mass	130.150 g·mol−1
Melting point	29-32 °C
Boiling point	220 to 223 °C (428 to 433 °F; 493 to 496 K)
Acidity (pKa)	0.60 [2]
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H315, H319, H335
Precautionary statements	P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y  verify  (what is  YN ?) Infobox references

A quinoxaline, also called a benzopyrazine, in organic chemistry, is a heterocyclic compound containing a ring complex made up of a benzene ring and a pyrazine ring. It is isomeric with other naphthyridines including quinazoline, phthalazine and cinnoline. ^[3] It is a colorless oil that melts just above room temperature. Although quinoxaline itself is mainly of academic interest, quinoxaline derivatives are used as dyes, pharmaceuticals (such as varenicline), and antibiotics such as olaquindox, carbadox, echinomycin, levomycin and actinoleutin.

Synthesis

They can be formed by condensing ortho-diamines with 1,2-diketones. The parent substance of the group, quinoxaline, results when glyoxal is condensed with 1,2-diaminobenzene. ^[4] Substituted derivatives arise when α-ketonic acids, α-chlorketones, α-aldehyde alcohols and α-ketone alcohols are used in place of diketones. ^[3] Quinoxaline and its analogues may also be formed by reduction of amino acids substituted 1,5-difluoro-2,4-dinitrobenzene (DFDNB): ^[5]

One study ^[6] used 2-iodoxybenzoic acid (IBX) as a catalyst in the reaction of benzil with 1,2-diaminobenzene:

Quinoxaline Synthesis

Uses

The antitumoral properties of quinoxaline compounds have been of interest. ^[7] Recently, quinoxaline and its analogs have been investigated as ligands. ^[8]

References

1. International Union of Pure and Applied Chemistry (2014). Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013. The Royal Society of Chemistry. p. 212. doi:10.1039/9781849733069. ISBN   978-0-85404-182-4.
2. Brown, H.C.; et al. (1955). Baude, E.A.; Nachod, F.C. (eds.). Determination of Organic Structures by Physical Methods. New York: Academic Press.
3.  One or more of the preceding sentences incorporates text from a publication now in the public domain :  Chisholm, Hugh, ed. (1911). "Quinoxalines". Encyclopædia Britannica . Vol. 22 (11th ed.). Cambridge University Press. p. 760.
4. 2,3-Pyrazinedicarboxylic Acid" Reuben G. Jones and Keith C. McLaughlin Org. Synth. 1950, 30, 86. doi : 10.15227/orgsyn.030.0086 . This paper describes the preparation of quinoxaline as an intermediate.
5. Xiang-Hong Wu; Gang Liu; et al. (2004). "Solution-phase reductive cyclization of 2-quinoxalinol analogs: Systematic study of parallel synthesis". Mol. Divers. 8 (2): 165–174. doi:10.1023/B:MODI.0000025639.89179.60. PMID   15209169. S2CID   28252647.
6. Heravi, Majid M. (2006). "Facile synthesis of quinoxaline derivatives using o-iodoxybenzoic acid (IBX) at room temperature". Arkivoc. 2006 (16): 16–22. doi: 10.3998/ark.5550190.0007.g02 . hdl: 2027/spo.5550190.0007.g02 .
7. Jean Renault; Michel Baron; Patrick Mailliet; et al. (1981). "Heterocyclic quinones.2.Quinoxaline-5,6-(and 5-8)-diones-Potential antitumoral agents". Eur. J. Med. Chem. 16 (6): 545–550.
8. Xianghong Wu; Anne E. V. Gorden (2007). "Regioselective Synthesis of Asymmetrically Substituted 2-Quinoxalinol Salen Ligands". J. Org. Chem. 72 (23): 8691–8699. doi:10.1021/jo701395w. PMID   17939720.