Title: Cinnoline
CAS Registry Number: 253-66-7
Additional Names: 1,2-Benzodiazine; benzo[c]pyridazine; 1,2-diazanaphthalene; a-phenodiazine
Molecular Formula: C8H6N2
Molecular Weight: 130.15
Percent Composition: C 73.83%, H 4.65%, N 21.52%
Literature References: First prepd by reduction of 4-chlorocinnoline: Busch, Rast, Ber. 30, 521, 524 (1897). Synthesis from methyl anthranilate: Jacobs et al., J. Am. Chem. Soc. 68, 1310 (1946); from cinnoline-4-carboxylic acid: Morley, J. Chem. Soc. 1951, 1971. Crystal and molecular structure: C. Huiszoon et al., Acta Crystallogr. 33B, 1867 (1977).
Properties: Pale yellow clusters of crystals from ligroin, mp 38°; also reported as mp 40-41° (Morley). Solvated needles from ether (contg 1 mol ether), mp 24-25°. bp0.35 114°. uv spectrum: Hearn et al., J. Chem. Soc. 1951, 3318. Geranium-like odor. Poisonous! Bitter taste resembling the taste of quinine. Must be kept under nitrogen. On exposure to air it has a tendency to liquefy and turn green. Strong base: ibid. 1949, 1356. Freely sol in the usual solvents.
Melting point: mp 38°; mp 40-41° (Morley); mp 24-25°
Boiling point: bp0.35 114°
Derivative Type: Hydrochloride
Molecular Formula: C8H6N2.HCl
Molecular Weight: 166.61
Percent Composition: C 57.67%, H 4.23%, N 16.81%, Cl 21.28%
Properties: Brownish needles from alcohol + ether, mp 156-160°. Volatilizes around 100° on slow heating. Freely sol in water, alcohol.
Melting point: mp 156-160°
Cinobufotalin Cinolazepam Cinoxate Cinromide Cintredekin Besudotox

Cinnoline numbering.png
Cinnoline molecule Cinnoline molecule
CAS number 253-66-7 YesY
PubChem 9208
ChemSpider 8853 YesY
ChEBI CHEBI:36617 YesY
Jmol-3D images Image 1
Molecular formula C8H6N2
Molar mass 130.15 g mol−1
Melting point 39 °C; 102 °F; 312 K
Acidity (pKa) 2.64[1]
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Cinnoline is an aromatic heterocyclic compound with the formula C8H6N2. It is isomeric with other naphthyridines including quinoxaline, phthalazine and quinazoline.