Cinnoline is a poisonous crystalline base, C8H6N2. It is isomeric with phthalazine, and prepared by boiling dihydrocinnolin dissolved in benzene with freshly precipitated mercuric oxide. The solution is filtered and the hydrochloride of the base precipitated by alcoholic hydrochloric acid; the free base is obtained as an oil by adding caustic soda. It may be obtained in white silky needles, melting at 24-25° C. and containing a molecule of ether of crystallization by cooling the oil dissolved in ether. The free base melts at 39° C. It is a strong base, forming stable salts with mineral acids, and is easily soluble in water and in the ordinary organic solvents. It has a taste resembling that of chloral hydrate, and leaves a sharp irritation for some time on the tongue; it is also very poisonous. Cinnoline derivatives are obtained from oxycinnolin carboxylic acid, which is formed by digesting orthophenyl propiolic acid diazo chloride with water. Oxycinnolin carboxylic acid on heating gives oxycinnolin, melting at 225°, which with phosphorus pentachloride gives chlorcinnolin. This substance is reduced by iron filings and sulfuric acid to dihydrocinnolin. Image File history File links Cinnoline_simple_structure. ... In chemistry, isomers are molecules with the same chemical formula and often with the same kinds of bonds between atoms, but in which the atoms are arranged differently. ... Benzene, also known as C6H6, PhH, and benzol, is an organic chemical compound which is a colorless and flammable liquid with a pleasant, sweet smell. ... In chemistry, hydrochlorides are salts resulting, or regarded as resulting from the reaction of hydrochloric acid with an organic base (mostly amine). ... The chemical substance hydrochloric acid is the aqueous (water-based) solution of hydrogen chloride (HCl) gas. ... Sodium hydroxide (NaOH), also known as caustic soda or lye in North America, is a caustic metallic base used in industry (mostly as a strong chemical base) in the manufacture of paper, textiles, and detergents. ... Chloral hydrate is a sedative and hypnotic drug, also known as trichloroacetaldehyde monohydrate, 2,2,2-trichloro-1,1-ethanediol, and the tradenames Aquachloral, Novo-Chlorhydrate, Somnos, Noctec, and Somnote. ... Structure of a carboxylic acid Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)-OH, usually written as COOH. The salts and anions of carboxylic acids are called carboxylates generally. ... Phosphorus Trichloride Phosphorus Pentachloride Phosphorus trichloride (PCl3) and phosphorus pentachloride (PCl5) are reactive chemicals used as chlorinating reagents in a chemical laboratory. ... Sulfuric acid (British English: sulphuric acid), H2SO4, is a strong mineral acid. ...

References

• This article incorporates text from the 1911 Encyclopædia Britannica, which is in the public domain.