Pyridine And Piperidine Alkaloids

PYRIDINE AND PIPERIDINE ALKALOIDS

Pyridine, also called azabenzene and azine, is a heterocyclic aromatic tertiary amine characterized by a six-membered ring structure composed of five carbon atoms and nitrogen which replace one carbon–hydrogen unit in the benzene ring (C₅H₅N). It is colourless, flammable, toxic liquid with unpleasant odor, miscible with water and with most organic solvents, boils at 115°C. Its aqueous solution is slightly alkaline. Pyridine is a base with chemical proper-ties similar to tertiary amines. Nitrogen in the ring system has an equatorial lone pair of electrons, which does not participate in the aromatic pi-bond. It is incompatible and reactive with strong oxidizers and strong acids, and reacts violently with chlorosulfonic acid, maleic anhydride, oleum, perchromates, β-propiolactone, formamide, chro-mium trioxide and sulphuric acid. Liquid pyridine easily evaporates into the air. If it is released to the air, it may take several months to years until it breaks down into other compounds. Pyridine compounds are found in nature. For example, nicotine from tobacco, ricinine from castor bean, pyridoxine or vitamin B and P products, etc.

Piperidine, hexa-hydropyridine, is a family of hetero-cyclic organic compound derived from pyridine through hydrogenation. It has one nitrogen atom in the cycle. It is a clear liquid with pepper-like aroma. It boils at 106°C, soluble in water, alcohol and ether. Piperidine derivative compounds are used as intermediate to make crystal derivative of aromatic nitrogen compounds containing nuclear atoms. They are used in manufacturing pharmaceuticals.