Simagchem Corp.

Uses 3.1 Solvent

Pyridine is a polar, basic, low-reactive solvent, especially for dehydrochlorination reactions and extraction of antibiotics. In elimination reaction, pyridine acts as the base of the elimination reaction and bonds the resulting hydrogen halide to form a pyridinium salt. In esterifications and acylations, pyridine activates the carboxylic acid halides or anhydrides.

3.2 Medicines

Pyridine's chemical structure can be found in various medications that are synthesized thanks in part to pyridine. One example is a medication called esomeprazole, the generic name for Nexium. This is a medication that's used to treat GERD, or gastroesophageal reflux disease. Another example of a pyridine containing medication is loratadine, more commonly known by its brand name of Claritin. Loratadine helps in the treatment of allergies.

3.3 Pesticides

The main use of pyridine is as a precursor to the herbicides paraquat and diquat. The first synthesis step of insecticide chlorpyrifos consists of the chlorination of pyridine. Pyridine is also the starting compound for the preparation of pyrithione-based fungicides. Cetylpyridinium and laurylpyridinium, which can be produced from pyridine with a Zincke reaction, are used as antiseptic in oral and dental care products. Pyridine is easily attacked by alkylating agents to give N-alkylpyridinium salts. One example is cetylpyridinium chloride.

Fig 3-1 Synthesis of paraquat

3.4 Synthesis of piperidine

Piperidine, a fundamental nitrogen heterocycle, is important synthetic building-block. Piperidines are produced by hydrogenation of pyridine with a nickel-, cobalt-, or ruthenium-based catalyst at elevated temperatures.

C5H5N + 3 H2 → C5H10NH 3.5 Ligand and Lewis base

Pyridine is widely used as a ligand in coordination chemistry. As a ligand of metal complex, it can be easily replaced by a stronger Lewis base, which can be used in the catalysis of polymerization and hydrogenation reactions. After the completion of reaction, pyridine ligand replaced during the reaction can be restored again. Pyridine is also used as a base in condensation reactions. As a base, pyridine can be used as the Karl Fischer reagent, but it is usually replaced by alternatives with a more pleasant odor, such as imidazole.

3.6 Others

Except for above uses, Pyridine is also used to product polycarbonate resins, vitamins, food flavorings, paints, dyes, rubber products, adhesives, and waterproofing for fabrics. Pyridine is added to ethanol to make it unsuitable for drinking. It is also used in the in vitro synthesis of DNA.

Toxicity information 4.1 Toxicity Level

Low Toxicity

4.2 Acute Toxicity

LD501580mg/kg (Large mice, oral); 1121mg/kg (Rabbit, through skin); inhaled by human 25mg/m3×20 min, irritation of conjunctiva and upper respiratory tract mucosa. Subacute and chronic toxicity: inhaled by large mice 32.3mg/m3×7 hours/day x5 days/week x6 months, increase in liver weight; inhaled by humans 20～40mg/m3 (long term), nerve damage, unsteady walking, digital tremors, low blood pressure, over-sweating, occasional liver and kidney damage.