Diboron

DescriptionDiborane 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.

UsesDiborane is used as a rocket propellant, in thevulcanization of rubber, as a polymerizationcatalyst, as a reducing agent, in the synthesisof trialkyl boranes, and as a doping agent(Merck 1996).

UsesDiborane is commonly used in the electronics industry for semiconductor doping by mixing small concentrations with silane in the gas phase prior to decomposition. When reacted with silane and oxygen, diborane also produces the cladding layers of wave guides for fiber optics by chemical vapor deposition. Other uses of diborane include the preparation of boron nitride by the reaction of diborane with ammonia, as a catalyst for polymerization, and for the conversion of olefins to trialkyl boranes. It is also used in the conversion of amines to amine boranes and as a selective reducing agent with carbonyl compounds such as aldehydes and ketones to form alcohols.

UsesAs 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.