LABORATORY CHEMICAL SAFETY SUMMARY: PYRIDINE

Substance

Pyridine

(Azabenzene; azine)

CAS 110-86-1

 

Formula

C5H5N

 

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

LD50 oral (rat)

891 mg/kg

 

LD50 skin (rabbit)

1121 mg/m3

 

PEL (OSHA)

5 ppm (15 mg/m3)

 

TLV-TWA (ACGIH)

5 ppm (15 mg/m3)

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.



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