化學PYRIDINE經常出現在反應中，其指甚麼

Pyridine is used as a base in many organic solution since the N atom in the pyridine molecule can absorb the proton generated during the reaction and it can then shift the equilibrium to the product side. The N in pyridine is an imine nitrogen which is not easily to be oxidized as amine. Also, it is less reactive towards the substitution reaction. It is a good base for an reaction.

Besides, pyridine is a good polar solvent with moderate boiling temperature slightly over 100C. This is good to be used for some reactions of polar substance and a basic medium is required. However, pyridine easily absorb a lot of water. It must purified to eliminate all the water before use.

Pyridine (「o比」啶) is a common organic compound with the following structure.

圖片參考：http://www.brenda.uni-koeln.de/Mol/Mol.image.php4?ID=15987&size=small

Its melting point is -42oC, boiling point 115.5oC, and density 0.9827 g cm-3. At room conditions, it is a colourless liquid which is miscible with water and many organic liquids.

In many organic reactions, pyridine is used as the solvent. For example, pyridine is usually used as a solvent in chlorination by SOCl2.