Physical and chemical properties, toxicity, and safety precautions of pyridine

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Physical and chemical properties, toxicity, and safety precautions of pyridine. Pyridine, C5H5N: 1. Aliases/English names: hexacyclotriene mononitrogen, azabenzene, nitrogen ring, heteroazobenzene; Pyridine. 2. Uses: pharmaceuticals, pesticides, color-developing agents, rubber accelerators, softeners, curing agents for synthetic resins, paint solvents, raw materials and solvents for organic synthesis, and chemical reagents for analysis. 3. Production method: Coal tar distillation. 4. Physical and chemical properties: Molecular weight: 79.10; Freezing point: -42°C; Boiling point: 115.3°C; Liquid density (26°C): 978 kg/m³; Flash point: -20°C; Auto-ignition temperature: 482.2°C; Refractive index (20°C): 1.5092; Explosive limit: 1.8%–12.4% (by volume). At normal temperature and pressure, pyridine is a flammable, toxic liquid that is colorless or slightly yellow in color and has an unpleasant, nauseating odor. It is soluble in water, alcohol, ether, and other organic solvents. Its aqueous solution is slightly alkaline. There is a risk of fire in the presence of sparks, high temperatures, or oxidizing agents. It reacts violently with sulfuric acid, nitric acid, chromic acid, fuming sulfuric acid, chlorosulfonic acid, maleic anhydride, silver perchlorate, etc., posing a risk of explosion. Its vapor can form an explosive mixture with air. The hazards associated with the contact of pyridine with certain substances are shown in the table below: Name of hazardous substance in combination with pyridine, Chemical formula, Hazard level, Summary. Sodium chlorate, Sodium perchlorate, Hydrogen peroxide, Sodium peroxide, Nitric acid, Sodium nitrate, Potassium permanganate, Nitric acid, Sulfuric acid, Chromium trioxide, Sodium hypochlorite, Sodium bromate, Potassium dichromate, Bromine trifluoride, Dinitrogen tetroxide, Fluorine, Formamide, Maleic anhydride (succinic anhydride). NaClO3, NaClO4, H2O2, Na2O2, NH4NO3, NaNO3, KMnO4, HNO3, H2SO4, CrO2, NaClO2, NaBrO3, K2Cr2O7, BrF3, N2O4, F2, HCONH2, HCCOHCCO. AA, A, BA, A, B, A, B, B, A, A, B, A. Fire may occur under certain conditions; there is a risk of intense fire reactions and heat release. Explosion may occur under certain conditions; intense decomposition occurs, producing gases. 5. Toxicity and safety measures: Maximum allowable concentration: 5 ppm. Pyridine can cause burns upon contact with the skin. Packaged in galvanized iron drums; it is a Class 1 flammable liquid. It should be stored in a cool, dry, and well-ventilated warehouse, away from sources of fire and heat, and should be kept separate from oxidizing agents and acidic substances. When storing, space should be left from the walls and ceiling. Avoid exposure to sunlight. Handle with care to avoid damaging the packaging. This post was last edited by ryn on 2009-1-5 12:08]