(Boroethane, boron hydride, diboron hexahydride)

CAS 19287-45-7





Physical Properties

Colorless gas

bp -93 °C, mp -165 °C

Rapidly decomposes in water to form hydrogen gas



Repulsive odor detectable at 1.8 to 3.5 ppm

Vapor Density

0.96 (air = 1.0)


Flash Point

-90 °C


Autoignition Temperature

38 to 52 °C


Toxicity Data

LC50 inhal (rat)

50 ppm (4 h)



0.1 ppm



0.1 ppm

Major Hazards

Highly toxic, flammable, and reactive gas; contact with air or halogenated compounds results in fires and explosions.


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.

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

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