Phthalazine

Phthalazine^[1]

Names
IUPAC name Phthalazine
Other names Benzo-orthodiazine 2,3-Benzodiazine Benzo[d]pyridazine
Identifiers
CAS Number	253-52-1
ChemSpider	8852
Jmol interactive 3D	Image
PubChem	9207
InChI InChI=1S/C8H6N2/c1-2-4-8-6-10-9-5-7(8)3-1/h1-6H Key: LFSXCDWNBUNEEM-UHFFFAOYSA-N InChI=1/C8H6N2/c1-2-4-8-6-10-9-5-7(8)3-1/h1-6H Key: LFSXCDWNBUNEEM-UHFFFAOYAE
SMILES C1=CC=C2C=NN=CC2=C1
Properties
Chemical formula	C8H6N2
Molar mass	130.15 g·mol^−1
Appearance	Pale yellow needles
Melting point	90 to 91 °C (194 to 196 °F; 363 to 364 K)
Boiling point	315 to 317 °C (599 to 603 °F; 588 to 590 K) (decomposition)
Solubility in water	Miscible
Acidity (pKa)	3.39[2]
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

Phthalazine, also called benzo-orthodiazine or benzopyridazine, is a heterocyclic organic compound with the molecular formula C₈H₆N₂. It is isomeric with other naphthyridines including quinoxaline, cinnoline and quinazoline.

Synthesis

Phthalazine can be obtained by the condensation of w-tetrabromorthoxylene with hydrazine, or by the reduction of chlorphthalazine with phosphorus and hydroiodic acid.

Properties

It possesses basic properties and forms addition products with alkyl iodides.

Reactions

Upon oxidation with alkaline potassium permanganate it yields pyridazine dicarboxylic acid. Zinc and hydrochloric acid decompose it with formation of orthoxylylene diamine. The keto-hydro derivative phthalazone (C₈H₆ON₂), is obtained by condensing hydrazine with orthophthalaldehydoacid. On treatment with phosphorus oxychloride, it yields a chlorphthalazine, which with zinc and hydrochloric acid gives isoindole (C₈H₇N), and with tin and hydrochloric acid, phthalimidine (C₈H₇ON), the second nitrogen atom being eliminated as ammonia.

References

1. Merck Index, 11th Edition, 7344.
2. 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.

•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.