Phthalazine

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.

Phthalazine^[1]

Names
Preferred IUPAC name Phthalazine[2]
Other names Benzo-orthodiazine 2,3-Benzodiazine Benzo[d]pyridazine
Identifiers
CAS Number	253-52-1 Y
3D model (JSmol)	Interactive image
ChemSpider	8852 N
ECHA InfoCard	100.005.422
PubChem CID	9207
UNII	91Y28DM24N Y
CompTox Dashboard (EPA)	DTXSID9049407
InChI InChI=1S/C8H6N2/c1-2-4-8-6-10-9-5-7(8)3-1/h1-6H N Key: LFSXCDWNBUNEEM-UHFFFAOYSA-N 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 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[3]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Synthesis

Phthalazine can be obtained by the condensation of ω-tetrabromorthoxylene with hydrazine, or by the reduction of chlorphthalazine with phosphorus and hydroiodic acid.^[4]

Properties

It possesses basic properties and forms addition products with alkyl iodides.^[4]

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^{[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.^[4]