Uses
As catalyst for olefin polymerization; as rubber vulcanizer; as reducing agent; as flame-speed accelerator; in rocket propellants; in intermediate in preparation of the boron hydrides; in conversion of olefins to trialkylboranes and primary alcohols; as a doping gas.
Air & Water Reactions
Highly flammable. Ignites spontaneously in moist air (forms hydrogen and boric acid), [Haz. Chem. Data (1966)]. Oxygen and Diborane form spontaneously explosive mixtures, [J. Amer. Chem. Soc. 76, 1997(1954)].
Reactivity Profile
Diborane is a colorless, air and moisture-sensitive gas, highly toxic. Diborane ignites in air. Diborane is very explosive when exposed to heat or flame, on contact with moisture Diborane produces hydrogen gas. Explosive reaction with benzene vapor, chlorine, nitric acid and tetravinyllead [Bretherick, 5th ed., 1995, p. 77]. Explosive reaction with dimethyl sulfoxide [Shriver, 1969, p. 209], violent reaction with halocarbon liquids used as fire extinguishants (e.g., carbon tetrachloride). Reaction with Al or Li produces complex hydrides that may ignite spontaneously in air [Haz. Chem. Data, 1975, p. 114].
Health Hazard
Boranes are highly toxic by inhalation, skin absorption or ingestion. They may produce acute or chronic poisoning. Diborane is an irritant to the lungs and kidneys. The primary effect of Diborane poisoning is lung congestion caused by local tissue irritation produced by the exothermic reaction of hydrolysis.
Health Hazard
Inhalation of diborane gas results in irritation of the respiratory tract and may result
in headache, cough, nausea, difficulty in breathing, chills, fever, and weakness. The
odor of diborane cannot be detected below the permissible exposure limit, so this
substance is considered to have poor warning properties. Overexposure to diborane
can cause damage to the central nervous system, liver, and kidneys. Death can result
from pulmonary edema (fluid in the lungs) and/or from lack of oxygen. Exposure to
diborane gas has not been found to have significant effects on the skin and mucous
membranes, but high concentrations can cause eye irritation, and contact with the
liquid can cause burns.
Chronic exposure to low concentrations of diborane may cause headache,
lightheadedness, fatigue, weakness in the muscles, and tremors. Repeated exposure
may produce chronic respiratory distress, particularly in susceptible individuals. An
existing dermatitis may also be worsened by repeated exposure to the liquid.
Diborane has not been shown to have carcinogenic or reproductive or developmental
effects in humans.
Fire Hazard
Diborane is a flammable gas that ignites spontaneously in moist air at room
temperature and forms explosive mixtures with air from 0.8% up to 88% by volume.
Diborane reacts with halogenated hydrocarbons, and fire extinguishing agents such
as Halon or carbon tetrachloride are therefore not recommended. Carbon dioxide
extinguishers should be used to fight diborane fires. Fires involving diborane
sometimes release toxic gases such as boron oxide smoke.
Fire Hazard
Diborane will ignite spontaneously in moist air at room temperature. Also, Diborane reacts violently with vaporizing liquid-type extinguishing agents. Diborane 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.
Potential Exposure
Diborane is used as the source of
boron in the semiconductor industry; as a catalyst for olefin
polymerization; a rubber vulcanizer; a reducing agent;
a flame-speed accelerator; a chemical intermediate for
other boron hydrides; as a doping agent; in rocket propel-
lants, and in the conversion of olefins to trialkyl boranes
and primary alcohols.
First aid
If this chemical gets into the eyes, remove any
contact lenses at once and irrigate immediately for at least
15 minutes, occasionally lifting upper and lower lids. Seek
medical attention immediately. If this chemical contacts the
skin, remove contaminated clothing and wash immediately
with soap and water. Seek medical attention immediately.
If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, includ-
ing resuscitation mask) if breathing has stopped and CPR if
heart action has stopped. Transfer promptly to a medical
facility. When this chemical has been swallowed, get medi-
cal attention. Give large quantities of water and induce
vomiting. Do not make an unconscious person vomit.
Medical observation is recommended for 24 to 48 hours
after breathing overexposure, as pulmonary edema may be
delayed. As first aid for pulmonary edema, a doctor or
authorized paramedic may consider administering a drug or
other inhalation therapy.
Shipping
UN1911 Diborane, Hazard Class: 2.3; Labels:
2.3-Poisonous gas, 2.1-Flammable gas Inhalation Hazard
Zone A. Cylinders must be transported in a secure upright
position, in a well-ventilated truck. Protect cylinder and
labels from physical damage. The owner of the compressed
gas cylinder is the only entity allowed by federal law
(49CFR) to transport and refill them. It is a violation of
transportation regulations to refill compressed gas cylinders
without the express written permission of the owner.
Incompatibilities
A strong reducing agent. Unstable above
8
C. The presence of contaminants may lower the autoigni-
tion temperature; ignition may take place at, or below,
room temperature. Diborane can polymerize, forming liquid
pentaborane (See P:0190). It ignites spontaneously in moist
air; and on contact with water, hydrolyzes exothermically
forming hydrogen and boric acid. Contact with halogenated
compounds (including fire extinguishers) may cause fire
and explosion. Contact with aluminum, lithium and other
active metals form hydrides which may ignite spontane-
ously. Incompatible with aluminum, carbon tetrachloride;
nitric acid; nitrogen trifluoride and many other chemicals.
Reacts with oxidized surfaces. Attacks some plastics,
rubber or coatings.
Description
Diborane is a colorless gas at room temperature
and atmospheric pressure. It has an unpleasant,
distinctive, sickly sweet odor. Diborane is a
highly flammable gas that forms a flammable
mixture with air over a range of 0.9 percent to
98 percent diborane (at 1 atm). Diborane bums
in air (or oxygen) with a blue to green flame.
Diborane is considered pyrophoric at room
temperature. The gas is easily ignited by a spark
or the heat of reaction with moisture in air.
Pure diborane is insensitive to mechanical
shock; however, shock and thermally sensitive
mixtures may be formed in the presence of impurities
such as oxygen, water, halogenated hydrocarbons,
and so on. Thermal decomposition
of diborane to hydrogen can result in excessive
pressure buildup. Vessels for containment
of diborane should be designed to contain
such resultant decomposition pressure.
Chemical Properties
Diborane is a compressed, colorless, and flam-
mable gas. It has a nauseating, sickly sweet odor.
Waste Disposal
Return refillable compressed
gas cylinders to supplier. Incineration with aqueous scrub-
bing of exhaust gases to remove B2O3 particulates.
Hazard
Diborane is pyrophoric and will ignite upon exposure to air. The boiling point is ?135°F and the flammable range is 0.8%–88% in air. The ignition temperature is 100° (37°C) to 140°F (60°C), and the flash point is 130°F (54°C). Diborane will react violently with halogenated fire-extinguishing agents, such as the halons. The four-digit UN identification number is 1911. The NFPA 704 designation is health 4, flammability 4, and reactivity 3. The white section of the diamond has a W with a slash through it, indicating water reactivity.
Flammability and Explosibility
Diborane is a flammable gas that ignites spontaneously in moist air at room temperature and forms explosive mixtures with air from 0.8% up to 88% by volume. Diborane reacts with halogenated hydrocarbons, and fire extinguishing agents such as Halon or carbon tetrachloride are therefore not recommended. Carbon dioxide extinguishers should be used to fight diborane fires. Fires involving diborane sometimes release toxic gases such as boron oxide smoke.
Materials Uses
Common metals are suitable as materials of
construction. These include the following metals
and metal alloys: chrome-molybdenum steel,
Type 300 stainless steel, brass, lead, Monel,
K-Monel, and nickel. Piping and appurtenances
for undiluted diborane must be designed by
experienced engineers and safety and fire protection specialists. Saran, polyethylene, Kel-F,
Teflon, graphite, and high-vacuum silicone
grease are satisfactory for use with diborane.
In addition to the ability of a material to withstand
chemical attack, the evaluation of materials
compatibility with diborane should also emphasize
the effect of the material on diborane
stability (as expressed by the decomposition
rate). The use of the following materials is not
recommended:
? Metal oxides
? Natural rubbers
? Neoprene
? Leak-lock
? Permatex
? Ordinary oil and grease
? Nordel 1145 RPT elastomer, unfilled and
Si02-filled
? silicon elastomer, unfilled and SiOrfilled
? CIS-4 polybutadiene elastomer, unfilled
and SiOrfilled
Physiological effects
ACGIH recommends a Threshold Limit Value-Time-
Weighted Average (TLV-TWA) of 0.1
ppm (0.11 mg/m3
) for diborane. The TLVTWA
is the time-weighted average concentration
for a normal 8-hour workday and a 40-hour
workweek, to which nearly all workers may be
repeatedly exposed, day after day, without adverse
effect.
OSHA lists an 8-hour Time-Weighted Average-
Permissible Exposure Limit (TWA-PEL)
of 0.1 ppm (0.1 mg/m3
) for diborane. TWAPEL
is the exposure limit that shall not be exceeded
by the 8-hour time-weighted average in
any 8-hour work shift of a 40-hour workweek
storage
diborane should be used only in a fume hood free of ignition sources and should be stored in a cold, dry, wellventilated area separated from incompatible substances and isolated from sources of sparks and open flames.
GRADES AVAILABLE
Diborane is sold in ambient or refrigerated cylinders
with a purity of 99 percent or greater. It
is commonly used in the electronics industry,
mainly in the form of dilute mixtures.
