Pyridine

PROPERTIES

Pyridine is a volatile, colorless or yellowish liquid with a distinctive, unpleasant fish-like odor. Unlimitedly soluble in water, readily soluble in alcohols, ethers, oils and benzene. It is stable, flammable, incompatible with strong oxidizing agents, strong acids.

APPLICATIONS

SOLVENT

Pyridine is a common aprotic but strongly polar solvent. It is widely used in the fine chemical and pharmaceutical industries. Pyridine is the solvent of choice for acylation and dehydrochlorination reactions. It is applied as a solvent in paint and rubber preparation, pharmaceuticals and in research laboratories for purposes such as extracting plant hormones. Pyridine is used as a solvent in manufacture of polycarbonate resins used in hand tools, camera parts, safety helmets, and electrical connectors. It is a solvent for anhydrous mineral salts.

There is deuterated pyridine, called pyridine-d₅, which is a solvent for ¹H NMR spectroscopy.

DENATURANT

Pyridine is used directly in the denaturation of ethyl alcohol, antifreeze mixtures or fungicides. Because it has a disagreable odor and a burning taste, it is added to chemicals to make them unsuitable for human consumption.

ANALYTICAL CHEMISTRY

Pyridine, along with barbituric acid, is used in colorimetric determinations of cyanide in aqueous matrices where red-colored dye is formed. The color intensity is directly proportional to cyanide concentration.

MANUFACTURE OF COMPOUNDS
Pyridine compounds are mainly used as intermediates to produce the pharmaceuticals and agrochemicals. Some of the pyridine compounds include pyridine-N-oxides, 2,6-disubstituted pyridines, substituted pyridines, dibromo pyridines, dichloro pyridines, acetyl pyridines, and many more. Approximately 20% of pyridine produced goes into the production of piperidine, which is commercially significant in the preparation of other important chemicals.

PHARMA

Pyridine is used in the manufacture of pharmaceuticals such as CNS stimulants, and local anesthetics. It is applied in the manufacture of vitamins (especially nicotinic acid), sulfa drugs. Pyridine is the intermediate for anti-infectives (including cetylpyridinium), antihistamines (including chloropheniramine maleate).

FOOD

Pyridine is used in food flavorings. In many cases there are complex compounds that contain pyridine. It can be found in seafood flavors and chocolate.

AGROCHEMICALS

Large amounts of pyridine are used as an intermediate in the manufacture of pesticides like herbicides (diquat, paraquat), insecticides (chlorpyrifo), fungicides (pyrithione).

Other uses:

Purification of mercury fulminate.

Thermal decomposition of flexible polyurethane foams.

Manufacture of explosives, rubber chemicals, adhesives.

Coupling reagent in azo dye manufacture.

Inhibitor, preparation of inhibitors.