BORON TRIFLUORIDE

Boron trifluoride
(Boron fluoride, trifluoroborane)
CAS 7637-07-2

BF₃

Colorless gas, fumes in moist air
bp -100 °C, mp -127 °C
Highly soluble in cold water (332 g/100 mL)

Pungent odor detectable at 1.5 ppm

2.4 (air = 1.0)

>1 mmHg at 20 °C

Noncombustible

LC₅₀ inhal (rat) 387 ppm (1070 mg/m³; 1 h)

PEL (OSHA) 1 ppm (3 mg/m³; ceiling)

TLV (ACGIH) 1 ppm (3 mg/m³; ceiling)

Highly corrosive to skin, eyes, and mucous membranes; reacts violently with water to form highly toxic HF.

Boron trifluoride (and organic complexes such as BF₃-etherate) are extremely corrosive substances that are destructive to all tissues of the body. Upon contact with moisture in the skin and other tissues, these compounds react to form hydrofluoric acid and fluoroboric acid, which cause severe burns. Boron trifluoride gas is extremely irritating to the skin, eyes, and mucous membranes. Inhalation of boron trifluoride can cause severe irritation and burning of the respiratory tract, difficulty breathing, and possibly respiratory failure and death. Exposure of the eyes to BF₃can cause severe burns and blindness. This compound is not considered to have adequate warning properties.

Boron trifluoride has not been found to be carcinogenic or to show reproductive or developmental toxicity in humans. Chronic exposure to boron trifluoride gas can cause respiratory irritation and damage.

Boron trifluoride gas is noncombustible. Water should not be used to extinguish any fire in which boron trifluoride is present. Dry chemical powder should be used for fires involving organic complexes of boron trifluoride.

Boron trifluoride reacts violently with water and alkali and alkaline earth metals such as sodium, potassium, and calcium. It may react exothermically with alkyl nitrates, ethylene oxide, and butadiene.

Boron trifluoride should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C, supplemented in the case of work with gaseous boron trifluoride with the procedures of Chapter 5.H. All work with boron trifluoride should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn to prevent eye and skin contact. Cylinders of boron trifluoride should be stored in locations appropriate for compressed gas storage and separated from alkali metals, alkaline earth metals, and other incompatible substances. Solutions of boron trifluoride should be stored in tightly sealed containers under an inert atmosphere in secondary containers.

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 boron trifluoride is inhaled, move the person to fresh air and seek medical attention at once. If this compound is ingested, obtain medical attention immediately.

In the event of accidental release of boron trifluoride gas, evacuate the area, and if the cause of the release is a leaking cylinder, remove the cylinder to a fume hood or open area if it is possible to do so safely. Positive pressure air-supplied respiratory protection and protective clothing may be necessary to deal with a leaking cylinder of boron trifluoride, and emergency response personnel should be notified.

Cylinders containing excess boron trifluoride should be returned to the manufacturer. Solutions of boron trifluoride should be labeled and disposed of according to your institution's disposal guidelines.

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.