Pyridine is a basic heterocyclic organic compound (C5H5N) widely used in agrochemicals, pharmaceuticals, and vitamins. It is a flammable, weakly alkaline liquid with a distinctive odor and can be isolated from coal tar or synthesized through various methods, including cyclization and laboratory preparation. The document also references key organic chemistry texts for further information.

1. PYRIDINE
Dr. J.FELICITA FLORENCE
ASSISTANT PROFESSOR

2. PYRIDINE
Pyridine is a basic heterocyclic organic compound with the molecular formula
C5H5N.

3. PROPERTIES
1. It is used in agrochemicals, pharmaceuticals and vitamins.
2. It is structurally related to benzene with one methine group
replaced by nitrogen atom.
3. Pyridine is a highly flammable ,weakly alkaline, water miscible
liquid with a defensive unpleasant smell.
4. It is colorless but older or impure samples can appear yellow.

4. Pyridine was first isolated by Anderson in 1851 from
bone oil

5. PREPARATION OF PYRIDINE

6. 1. ISOLATION OF PYRIDINE FROM COAL TAR
The light oil fraction of coal tar contains besides pyridine and alkyl pyridines,
aromatic hydrocarbons. It occurs to the extend of 0.1% in coal tar from which it is
obtained commercially.

8. Pyridine is obtained by passing a mixture of acetylene and hydrogen
cyanide through a red hot tube
2. BONNEMANN CYCLIZATION
Acetylene Acetylene

9. 3. Pyridine is prepared by heating with Pentamethylene diamine
Hydrochloride and then oxidising the product with Piperidine and
Concentrated Sulphuric acid at 300°C
Piperidine

10. The first step of the synthesis is the condensation of 2 moles of 3-dicarbonyl
compound with 1 mole of an aldehyde and 1 mole of ammonium . The
dihydropyridine derivative obtained from the first step is on oxidation with Nitric
acid/FeCl3 yields pyridine.

11. 5. A laboratory preparation of pyridine includes distillation of
nicotinic acid with soda lime (NAOH+CaO)

12. REFERENCES
1.Organic Chemistry by D.S. Tewari.
2. Modern Organic Chemistry by M.K.Jain and S.C. Sharma.