Diborane chemical reactions

A direct comparison between porous carbon and porous silica supports is difficult since the measurement conditions are different. In the case of silica the hydrogen release temperature is lower but a possible chemical reaction between the silica and the LiB H4 has to be considered. It is interesting that the porous carbon support seems to suppress the formation of diborane. 

Brown s investigation of the addition compounds of trimethyl borane, diborane, and boron trifluoride with amines has provided a quantitative estimation for steric strain effects in chemical reactions. He also investigated the role of steric effects in solvolytic, displacement, and in elimination reactions. His results demonstrate that steric effects can assist, as well as hinder, the rate of a chemical reaction. 

Some cylinders have contents that change their chemical characteristic over time (decompose, polymerize, etc.). Examples include 1,3-butadiene, hydrogen bromide and diborane. These changes may eventually result in overpressurization that exceeds the specification of the cylinder. This situation renders the cylinder unsafe for transport. Contents of cylinders that have become contaminated with foreign material may also result in a chemical reaction causing overpressurization or an explosive hazard. These cylinders should be handled with extreme care and only by specially trained and qualified personnel. 

Chemical Reactivity - Reactivity with Water Reacts to form flammable hydrogen gas Reactivity with Common Materials Reacts with acids to form toxic, flammable diborane gas. Slowly attacks and destroys glass Stability During Transport Stable unless contaminated with acids or is overheated, thereby forming flammable hydrogen gas Neutralizing Agents for Acids and Caustics Caustic formed by the reaction with water can be diluted with water and then neutralized with acetic acid Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

Reduction reactions are perhaps the second most common type of potentially hazardous reactions. Materials such as metallic sodium, aluminium, and magnesium hydrazine diborane sodium hydride and hydrogen have all been involved in a wide variety of chemical accidents. 

Shore, S. G., and R. W. Parry Chemical Evidence for the Structure of the Diammoniate of Diborane , III. The Reactions of Borohydride Salts with Eithium Halides and Aluminium Chloride. J. Amer. chem. Soc. 80, 12 (1958). 

The diborane solution was obtained from Aldrich Chemical Company, Inc. It was titrated4 before use although the submitter states that this is not necessary. The solution was transferred from the stock solution to the reaction flask via a cannula. The checkers first transferred the diborane... 

Silicon Dioxide. Si02 layers produced by PECVD are useful for intermetal dielectric layers and mechanical or chemical protection and as diffusion masks and gate oxides on compound-semiconductor devices. The films are generally formed by the plasma-enhanced reaction of SiH4 at 200-300 °C with nitrous oxide (N20), but CO, C02, or 02 have also been used (238-241). Other silicon sources including tetramethoxysilane, methyl dimethoxysilane, and tetramethylsilane have also been investigated (202). Diborane or phosphine can be added to the deposition atmosphere to form doped oxide layers. 

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. 

Chemical methods are generally based on the reaction of surface hydroxyl groups with a selectively reacting compound to form a covalently bonded surface species of well known composition. As reactive compounds, diborane,4,5 boron trichloride,6,7 diazomethane,8 organosilanes,3,6,9,10,11,12,13,14 and organometallic compounds15 have been employed. a0H is then derived from the amount of the chemisorbed species as well as the amount of volatile reaction products. 

CAB 2, R = H, derived from monoacyloxytartaric acid and diborane is also an excellent catalyst (20 mol %) for the Mukaiyama condensation of simple enol silyl ethers of achiral ketones with various aldehydes. The reactivity of aldol-type reactions can, furthermore, be improved, without reducing the enantioselectivity, by use of 10-20 mol % of 2, R = 3,5-(CF3)2C6H3, prepared from 3,5-bis(trifluoromethyl)phenyl-boronic acid and a chiral tartaric acid derivative. The enantioselectivity could also be improved, without reducing the chemical yield, by using 20 mol % 2, R = o-PhOCgH4, prepared from o-phenoxyphenylboronic acid and chiral tartaric acid derivative. The CAB 2-catalyzed aldol process enables the formation of adducts in a highly diastereo- and enantioselective manner (up to 99 % ee) under mild reaction conditions [47a,c]. These reactions are catalytic, and the chiral source is recoverable and re-usable (Eq. 62). 

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