Safety diborane

Diborane(6), B2H. This spontaneously flammable gas is consumed primarily by the electronics industry as a dopant in the production of siHcon wafers for use in semiconductors. It is also used to produce amine boranes and the higher boron hydrides. Gallery Chemical Co., a division of Mine Safety AppHances Co., and Voltaix, Inc., are the main U.S. producers of this substance. Several hundred thousand pounds were manufactured worldwide in 1990. 

Safety considerations are paramount in any boron hydride synthesis. The energy yield from the oxidations of boron hydrides is too high for any cavalier treatment of boron hydrides. Exclusion of air is the critical consideration in diborane reactions. Decaborane(14) is less reactive, generally, in a kinetic sense, but the thermodynamic potential is comparable. In addition, all volatile boron hydrides are toxic. The procedures described in the latter two preparations are within our experience non-hazardous. These procedures should be followed in every detail improvisation is not recommended. 

Diborane in air may be analyzed by passing air through a PTFE filter and oxidizer-impregnated charcoal. It is oxidized to boron and desorbed with 3% H2O2. Boron is measured by plasma emission spectrometry or ICP emission spectrometry (NIOSH. 1984. Manual of Analytical Methods, 3rd ed. Cincinnati, OH National Institute for Occupational Safety and Health). Boron hydrides can be analyzed by FTIR techniques. 

The addition of a gas to a reaction mixture (commonly the hydrogen halides, fluorine, chlorine, phosgene, boron trifluoride, carbon dioxide, ammonia, gaseous unsaturated hydrocarbons, ethylene oxide) requires the provision of safety precautions which may not be immediately apparent. Some of these gases may be generated in situ (e.g. diborane in hydroboration reactions), some may be commercially available in cylinders, and some may be generated by chemical or other means (e.g. carbon dioxide, ozone). An individual description of the convenient sources of these gases will be found under Section 4.2. 

Caution. Diborane(6) is a highly toxic, extremely flammable gas (bp — 86.5°). Serious explosions have resulted from exposure of diborane(6) to atmospheric oxygen. All apparatus to be used for handling diborane(6) should be checked carefully for leaks. Suitable safety shields should be employed. 

Caution Carry out all procedures in a well-ventilated hood, and wear disposable vinyl or latex gloves and chemical-resistant safety goggles. Diborane is a flammable and highly irritating compound. 

National Institute for Occupational Safety and Health (NIOSH). Pocket guide to chemical hazards. 2005. Diborane. NIOSH publication no. 149, Washington, D.C. NIOSH. 

SAFETY PROFILE Moderately toxic by inhalation. A severe eye, skin, and mucous membrane irritant. Explodes on contact with dioxygen difluoride. Violent reaction or ignition with borane, diborane, F2. hexafluoroisopropylideneamino lithium, O2. Win react with water or steam to produce toxic and corrosive fumes. Dangerous when heated to decomposition it emits highly toxic fumes of F" and PO. See also HYDROFLUORIC ACID, FLUORIDES, and PHOSPHORUS PENTAFLUORIDE. 

Diborane is valued as a fuel for use in rocket propellants. Gallery Ghemical Co. developed equipment and procedures for the safe handling of diborane and by 1962 had produced about 5 million pounds of the material. It is offered for shipment in chrome-molybdenum steel cylinders at —80° (minimum order 100 g.), and technical bulletins present information on handling procedures and safety precautions. 

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 pro-... 

Diborane Health and Safety Bulletin, 1982, Gallery Chemical Company, P.O. Box 429, Pittsburgh, PA 15230. 

The U.S. Occupational Safety and Health Administration has established an eight-hour time-weighted average exposure limit of 0.1 ppm (0.1 mg/VO ) for diborane which is also the threshold limit value (TLV) adopted by the American Conference of Governmental Industrial Hygienists. [2] and [3]... 

As diborane is a toxic gas, the doping should be carried out in a leaktight deposition chamber with a safety gas feed system. For this reason, some people use only B powder in the CVD chamber for doping (9). Using B2O3 (boron trioxide) powder mixed in a liquid is another... 

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