Boron gaseous hydrogen

Boron, which is used to make composites, is deposited on a tungsten wire when the wire is heated electrically in the presence of boron trichloride vapor and gaseous hydrogen. Write a balanced equation for the reaction. 

The addition compound of trimethylamine and monochloro-borane was first synthesized by the reaction of gaseous hydrogen chloride with trimethylamine-borane at low temperature in a vacuum line. Although boron trichloride4 or mereury(II) chloride5 can be used, the first method can easily be modified for large-scale runs by using aqueous concentrated hydrochloric acid.5 No special precautions for the exclusion of air or water are necessary. 

The alkylation of paraSins with olefins to yield higher molecular weight branched-chain paraffins may be carried out thermally or catalyt-ically. The catalysts for the reaction fall into two principal classes, both of which may be referred to as acid-acting catalysts (1) anhydrous halides of the Friedel-Crafts type and (2) acids. Representatives of the first type are aluminum chloride, aluminum bromide, zirconium chloride, and boron fluoride gaseous hydrogen halides serve as promoters for these catalysts. The chief acid catalysts are concentrated sulfuric acid and liquid hydrogen fluoride. Catalytic alkylations are carried out under sufficient pressure to keep at least part of the reactants in the liquid phase. 

In a typical process adiponitrile is formed by the interaction of adipic acid and gaseous ammonia in the presence of a boron phosphate catalyst at 305-350°C. The adiponitrile is purified and then subjected to continuous hydrogenation at 130°C and 4000 Ibf/in (28 MPa) pressure in the presence of excess ammonia and a cobalt catalyst. By-products such as hexamethyleneimine are formed but the quantity produced is minimized by the use of excess ammonia. Pure hexamethylenediamine (boiling point 90-92°C at 14mmHg pressure, melting point 39°C) is obtained by distillation, Hexamethylenediamine is also prepared commercially from butadience. The butadiene feedstock is of relatively low cost but it does use substantial quantities of hydrogen cyanide. The process developed by Du Pont may be given schematically as ... 

Trimethylamine replaces PH3 quantitatively in BH3 PH3 to give BH3 N(CH3)3. Liquid or gaseous ammonia also replaces phosphine in the compound BH3 PH3 to the extent of 52-58% or up to 75%, respectively. The hydrogen atoms bonded to boron are partially, or completely, replaced by chlorine on treatment with hydrogen chloride, depending on the reaction conditions. The first stage of the reaction with hydrogen chloride is the formation of the colourless, viscous liquid BHjCl PH3 (see below). 

In the second step, trichlorosilane is formed by the reaction of the silicon with anhydrous hydrogen chloride, HCl. The reaction of the sohd silicon and gaseous HCl occurs at 300°C in the presence of a catalyst. This step is important to purification, since chlorides of the aluminum and boron impurities also are formed. The resulting... 

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. 

Figure IV. A. 3. is a heat of combustion plot of the elements with fluorine as the oxidizer. One can carry through the same arguments as those made for the oxygen plot except it is well to remember that many of the metal fluorides are gaseous under the combustion chamber conditions that prevail. Since BF is a gas, the significance of boron compounds as fuels with fluorine oxidizers particularly changes for the better. Comparison of figures IV. A. 1. and IV. A. 3. will show that H2 -02 and H2 - F2 have the same standard state heat release. Yet above it was stated that the specific impulse with hydrogen-fluorine was the greater. This comparison again points out the limitations of the plots, which do not take into account the diss-...

We believe the use of a direct gaseous phase fluorination process for modifying the surface and structure of zeolites to be a new process (18). The literature does contain references to the use of hydrogen fluoride (20, 22, 23), boron trifluoride (21, 24), aluminum monofluoride (sic) (19) and silica difluoride (sic) (19) to treat the surface of a zeolite to obtain higher catalytic activity. However, the use of fluorine gas to modify both surface and structure has not been reported before. The purpose of this paper is to report results of fluorination of zeolites and to describe the process involved in such a treatment. Detailed results on fluorine-treated zeolites and their unusual properties, both adsorptive and catalytic, will be discussed in forthcoming papers. 

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