Isoquinoline (Isoquinoline), namely benzopyridine, is a heterocyclic compound derived by replacing a β-CH group in naphthalene with nitrogen. It is isomers with quinoline and has aromaticity.
Nature
Isoquinoline is a colorless low-melting flaky crystal, solid or liquid, with an aroma similar to a mixture of anise oil and benzaldehyde, and usually turns yellow in color after storage. Exist in coal tar and bone oil. Slightly soluble in water, soluble in dilute acid, miscible with various organic solvents. Can evaporate with water vapor. Absorbent. Alkaline, pKa = 5.4, stronger than quinoline, slightly stronger than pyridine, can form salt with various acids, and its hydrochloride melting point is 209°C.
Production
In industry, the crude quinoline fraction of coal tar is mainly used as raw material, and isoquinoline is produced through sulfonation, fractional crystallization, filtration, recrystallization, ammonia decomposition, washing and rectification.
use Isoquinoline can be used as an intermediate for synthesizing drugs, dyes, pesticides and as a stationary liquid for gas chromatography. Isoquinoline derivatives widely exist in nature, and there are more than 1,000 known isoquinoline alkaloids, which are the largest class of known alkaloids. They mostly Use
Isoquinoline or tetrahydroisoquinoline as the core, and can be subdivided into isoquinolines, benzylisoquinolines, bisbenzylisoquinolines, and apofens according to the linking group. , the original berberine class, proto class, emetine class, α-naphenanthridine class and morphine class of nine types of alkaloids. There are many drugs that are derivatives of isoquinolines. The well-known isoquinoline alkaloid papaverine is still an important antispasmodic drug. The antidepressant nomifensine and the antischistosomal drug praziquantel are derived from tetrahydroisoquinoline.