Diborane

  • Boroethane
  • Boron hydride
  • Diboron hexahydride
Formula
B2H6
Structure
Description
Diborane is a colorless gas with an offensive odor.
Uses
Intermediate for trialkyl & triaryl boranes (polymerization catalyst), copolymerization catalyst for styrene & butadiene, polymerization catalyst for olefins & epoxides, & for prodn of hard boron coatings on metals & ceramics, in rocket propellants, as rubber vulcanizer, reducing agent, & flame-speed accelerator, as doping gas.

Registry Numbers and Inventories.
CAS
19287-45-7
EC (EINECS/ELINCS)
242-940-6
RTECS
HQ9275000
RTECS class
Mutagen
UN (DOT)
1911
Merck
12,3062
Beilstein/Gmelin
1295 (G)
Swiss Giftliste 1
G-1506
Canada DSL/NDSL
DSL
US TSCA
Listed
New Zealand
Listed
Japan ENCS (MITI)
Listed
Korea ECL
Listed

Properties.
Formula
B2H6
Formula mass
27.67
Melting point, °C
-165.0
Boiling point, °C
-87
Vapor pressure, mmHg
224
Vapor density (air=1)
1
Odor Threshold Odor threshold 2 mg/m3
Critical temperature
16.7
Critical pressure
39.5
Density
0.447 g/cm3 (20 C)
Solubility in water
Reacts
Viscosity
gas: 0.00785 MPa. s @ 10C. liquid: 0.177 MPa s @ -109.2C.
Surface tension
18.6 g/s2 @ 121.6 C

Hazards and Protection.
Storage
Keep in a cool, dry, dark location in a tightly sealed container or cylinder. Keep away from incompatible materials, ignition sources and untrained individuals. Secure and label area. Protect containers/cylinders from physical damage.
Handling
All chemicals should be considered hazardous. Avoid direct physical contact. Use appropriate, approved safety equipment. Untrained individuals should not handle this chemical or its container. Handling should occur in a chemical fume hood.
Protection
Wear appropriate protective gloves, clothing and goggles -- as recommended by the manufacturer. Always wear thermal protective clothing when handling refrigerated/cryogenic liquids.
Respirators
Wear positive pressure self-contained breathing apparatus (SCBA).
Small spills/leaks
Keep sparks, flames, and other sources of ignition away. Keep material out of water sources and sewers. Attempt to stop leak if without undue personnel hazard. Use water spray to knock-down vapors.
Stability
Reactive under confinement or with heat.
Incompatibilities
Reaction with Al or Li produces complex hydrides that may ignite spontaneously in air.

Fire.
Flash Point,°C
-90
Autoignition, °C
40-50
Upper exp. limit, %
98
Lower exp. limit, %
0.8
Fire fighting
Firefighting should be done from an explosion-resistant location. Use water from unmanned monitors or hose holders to keep fire-exposed containers cool. If it is necessary to stop flow of gas, use water spray to protect personnel effecting shut-off. Personnel should be evacuated immediately. Self-contained breathing apparatus and full protective clothing should be worn. Isolate for 1/2 mile in all directions if tank car or truck is involved in fire.Inert gas substances such as liquid nitrogen are recommended as fire extinguishing agents.
Fire potential
Very flammable. Combustion imminent. Very hazardous.
Hazards
It will ignite spontaneously in moist air at room temperature. Also, it reacts violently with vaporizing liquid-type extinguishing agents. It hydrolyzes in water to hydrogen and boric acid. Incompatible with air, halogenated compounds, aluminum, lithium, active metals, oxidized surfaces, chlorine, fuming nitric acid, nitrogen trifluoride, oxygen, and phosphorus trifluoride. Avoid moist air, electrical sparks, open flames or any other heat source. Hazardous polymerization may occur.
Combustion products
Toxic gases and vapors (such as boron oxide smoke) may be released in a fire involving diborane.
Health
4
 
Flammability
4
 
 
Reactivity
3
 
 
Special
W

Health.
Exposure limit(s)
TLV: 0.1 ppm; 0.11 mg/m3 (as TWA) (ACGIH 1990-1991). OSHA PEL: TWA 0.1 ppm (0.1 mg/m3) NIOSH REL: TWA 0.1 ppm (0.1 mg/m3) NIOSH IDLH: 15 ppm
Poison_Class
2
Exposure effects
Cough, wheezing, rapid breathing, mild elevated blood pressure, or fever may be noted after exposure to diborane. Dizziness, weakness, CNS depression, and incoordination have been seen, but diborane is less active for neurological effects than pentaborane or decaborane. Coma and seizure generally do not occur with diborane. No data were found for diborane for possible effects on teratogenesis, pregnancy, or lactation.
   Ingestion
Nausea is one of the first symptoms seen. Anorexia and hypersalivation have been reported with diborane exposure.
   Inhalation
May be toxic/fatal if inhaled. Contact may cause burns, severe injury and/or frostbite.
   Skin
Diborane is an irritant of the skin and mucous membranes. Reddened skin may occur from exposure to the vapor. The liquid can cause blisters.
   Eyes
Diborane is an eye and mucous membrane irritant. Headache has been noted after spills and low level exposures to pentaborane or decaborane. Borohydrides have caused irreversible eye damage.

First aid
 
   Ingestion
Ingestion of diborane is extremely unlikely as it is a gas at ambient temperatures.
   Inhalation
Move patient to fresh air. Monitor for respiratory distress. If cough or difficulty breathing develops, evaluate for respiratory tract irritation, bronchitis, or pneumonitis. Administer oxygen and assist ventilation as required. Treat bronchospasm with beta2 agonist and corticosteroid aerosols.
   Skin
Remove and isolate contaminated clothing and shoes. Immediately flush with running water for at least 20 minutes. In case of contact with liquefied gas, thaw frosted parts with lukewarm water.
   Eyes
Irrigate exposed eyes with copious amounts of tepid water for at least 15 minutes. If irritation, pain, swelling, lacrimation, or photophobia persist, the patient should be seen in a health care facility.

Transport.
UN number
1911
Response guide
Hazard class
2.1
PRTC
T
USCG CHRIS Code
DIR
 
Std. Transport #
4920107