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

Odor Threshold Odor threshold 2 mg/m3
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
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.
NFPA 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 119
Hazard class 2.1
PRTC T
USCG CHRIS Code DIR  
Std. Transport # 4920107