LCSS: PYRIDINE

Substance	Pyridine (Azabenzene; azine) CAS 110-86-1
Formula	CHN
Physical Properties	Colorless or pale yellow liquid bp 115 °C, mp -42 °C Miscible with water
Odor	Nauseating odor detectable at 0.23 to 1.9 ppm (mean = 0.66 ppm)
Vapor Density	2.72 at bp (air = 1.0)
Vapor Pressure	18 mmHg at 20 °C
Flash Point	20 °C
Autoignition Temperature	482 °C
Toxicity Data	LD oral (rat) 891 mg/kg LD skin (rabbit) 1121 mg/m PEL (OSHA) 5 ppm (15 mg/m) TLV-TWA (ACGIH) 5 ppm (15 mg/m)
Major Hazards	Highly flammable liquid
Toxicity	The acute toxicity of pyridine is low. Inhalation causes irritation of the respiratory system and may affect the central nervous system, causing headache, nausea, vomiting, dizziness, and nervousness. Pyridine irritates the eyes and skin and is readily absorbed, leading to systemic effects. Ingestion of pyridine can result in liver and kidney damage. Pyridine causes olfactory fatigue, and its odor does not provide adequate warning of the presence of harmful concentrations. Pyridine has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans. Chronic exposure to pyridine can result in damage to the liver, kidneys, and central nervous system.
Flammability and Explosibility	Pyridine is a highly flammable liquid (NFPA rating = 3), and its vapor can travel a considerable distance and "flash back." Pyridine vapor forms explosive mixtures with air at concentrations of 1.8 to 12.4% (by volume). Carbon dioxide or dry chemical extinguishers should be used for pyridine fires.
Reactivity and Incompatibility	Pyridine may react violently with dinitrogen tetroxide, acid chlorides and anhydrides, perchloric acid, and strong oxidizing agents.
Storage and Handling	Pyridine should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C. In particular, pyridine should be used only in areas free of ignition sources, and quantities greater than 1 liter should be stored in tightly sealed metal containers in areas separate from oxidizers.
Accidents	In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If pyridine is ingested, obtain medical attention immediately. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once. In the event of a spill, remove all ignition sources, soak up the pyridine with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area.
Disposal	Excess pyridine and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines. For more information on disposal procedures, see Chapter 7 of this volume.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright© 1995 National Academy of Sciences. All rights reserved.

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