Collidine

Collidine is the common name for 2,4,6-trimethylpyridine, a member of the pyridine family of heteroaromatic amines. The molecule has three methyl substituents on the ring at the 2-, 4-, and 6-positions, giving a hindered, basic aromatic amine. While collidine most often refers to this specific isomer, the name is sometimes used more broadly for methylpyridines in general. Its chemical formula is C8H11N.

Collidine is typically encountered as a colorless to pale yellow liquid with a strong, characteristic pyridine-like odor. It is miscible with many organic solvents and has limited water solubility. It is relatively stable under normal laboratory conditions but should be stored in a well-ventilated area away from oxidizers and incompatible materials. In the laboratory, collidine readily forms salts with acids, such as collidinium salts, and is sometimes used as a non-nucleophilic base due to steric hindrance around the ring, which reduces its nucleophilicity.

In practical use, collidine serves as a base and acid scavenger in various organic syntheses. It is employed to trap acidic byproducts and to facilitate reactions such as acylations and condensations where a mild, hindered base is advantageous. It can also function as a solvent or co-solvent in certain industrial or research processes.

Safety and handling considerations apply to collidine as with many aromatic amines. It can be irritating to the skin, eyes, and respiratory tract and should be handled with appropriate personal protective equipment in a fume hood. Waste disposal should follow applicable regulations for hazardous organic amines.