Phthalazine

Phthalazine^[1]
Names
	IUPAC name Phthalazine
	Other names Benzo-orthodiazine; 2,3-Benzodiazine; Benzo[d]pyridazine
Identifiers
CAS Number	253-52-1 ;
3D model (JSmol)	Interactive image;
ChemSpider	8852 ;
ECHA InfoCard	100.005.422
PubChem CID	9207;
CompTox Dashboard (EPA)	DTXSID9049407 ;
	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	130.150 g·mol−1
Appearance	Pale yellow needles
Melting point	90 °C (194 °F; 363 K)
Boiling point	315 °C (599 °F; 588 K)
Solubility in water	Miscible
Acidity (pKa)	3.39
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) 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.

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

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^{[citation needed]}. 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.

^ Merck Index, 11th Edition, 7344.
^ 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. {{cite encyclopedia}}: Missing or empty |title= (help)