Boron trichloride determination

Bis(dichloroboryl)benzene (6) is an important starting material which lends itself to facile derivatization. As shown by Piers, it cleanly reacts with bis(penta-fluorophenyl)zinc to afford the corresponding bidentate Lewis acid 13 (Scheme 7) The molecular structure of diborane 13 has been determined and is shown in Fig. 1. In this structure, the vicinal boron atoms are held at 3.26 A and from one another and seem to be ideally positioned to cooperatively interact with monoatomic anions. The fully fluorinated version of this bidentate Lewis acid has also been prepared. Original efforts focused on the use of 1,2-bis(dichloroboryl)tetrafluorobenzene 14 as a starting material (Scheme 8). This compound could be observed in the early stage of the reaction of trimeric perfluoro-o-phenylenemercury (4) with boron trichloride, but was found to be unstable toward condensation into 9,10-dichloro-9,10-dihydro-9,10-diboraoctafluoroanthracene 15. The successful synthesis of the fully fluorinated... 

The structures of l,8-di(silyl)naphthalene and its mono- and di(p-anisyl) derivatives have been determined and are shown in Fig. 3-5. While the naphthalene part of the molecules appears to be largely undistorted, the two silyl groups are clearly bent away from each other in the molecular plane in order to avoid closer repulsive contacts. This steric crowding enhances the chemical reactivity of the molecule and makes the eompound a versatile starting material for numerous derivatives. For substitution control the conversion into the symmetrical dichlorosilane is possible using boron trichloride (Scheme 5). 

The results of this analysis are presented in a dimensionless form readily applicable to a range of preform thicknesses, fiber diameters, fiber volume fractions, and deposition chemistries. To illustrate the application of these results to a practical problem, the optimum process conditions are determined for a sample problem in which a boron nitride coating is deposited from boron trichloride and ammonia. 

The polarisation along the bond is characterised by both its magnitude and its direction, i.e. it is a vector. This may be illustrated by considering a molecule of boron trichloride, which has a symmetrical planar trigonal shape. First, consider an isolated B-Cl bond and determine the direction of polarisation,... 

Trace amounts of chloro derivatives of hydrocarbons in boron trichloride were determined using a thermionic detector after boron trichloride had been combined with diphenylamine applied in an amount of 20% on INZ-600 [48]. 

The following technique for the analysis of easily hydrolysable compounds is particularly valuable and sufficiently universal. In trace analysis and calibration of chromatographs by means of easily hydrolysable compounds one can suppress the hydrolysis of the trace component by preparing it in a substance which can be hydrolysed more easily. For example, in the determination of trace amounts of silicon tetrachloride its solutions in boron trichloride are used for calibration [98]. 

Initiator derived end group in a polymer may be determined by chemical analysis, e.g. methyl methacrylate polymerization initiated by t-butoxy radicals. The t-butoxy end group may be cleaved off with boron trichloride and the t-butyl chloride produced can then be quantified. Evaluation of the amounts of acetone and t-butanol formed during polymerization indicates the percentage of p-scission and abstraction from monomer re.spectively. 

Disposal of boron trichloride by neutralizing, scrubbing, or by other means may be subject to permitting by federal, state or provincial regulations. Persons involved with disposal of boron trichloride should check with the environmental authorities having jurisdiction to determine the applicability of permitting regulations to disposal activities. 

Brazhnikov and Sakodynskii determined the retention time of boron trichloride on various supports and stationary phases and compared its behaviour to that of boronalkyls, Zelyaev et al used a molybdenum glass column packed with poly (methylsiloxane) on Spherchrom 1 to separate in amounts down to O.lppm of various trace impurities in boron trichloride, such as chlorine, phosgene, silicon tetrachloride, chloroform, carbon tetrachloride and dichloroethane. They used a column temperature of 60°C with nitrogen as carrier gas and employed thermionic and flame ionization detectors,... 

Boron.—Reactions of boron trichloride with aromatic amines may proceed by formation of the Cl3B,NH2R adduct and then by hydrogen chloride elimination to give ClaB=NHR en route to the ultimate product (CIB—NR),. The mechanism of these reactions has been probed by isolation and characterization of intermediates, and stoicheiometric and kinetic studies -the kinetics can be followed by monitoring the evolution of hydrogen chloride. Photochemical reaction of triethylboron with iodine in cyclohexane takes place by a free-radical mechanism, indicated by the determined rate law. ... 

Phillips and Timms [599] described a less general method. They converted germanium and silicon in alloys into hydrides and further into chlorides by contact with gold trichloride. They performed GC on a column packed with 13% of silicone 702 on Celite with the use of a gas-density balance for detection. Juvet and Fischer [600] developed a special reactor coupled directly to the chromatographic column, in which they fluorinated metals in alloys, carbides, oxides, sulphides and salts. In these samples, they determined quantitatively uranium, sulphur, selenium, technetium, tungsten, molybdenum, rhenium, silicon, boron, osmium, vanadium, iridium and platinum as fluorides. They performed the analysis on a PTFE column packed with 15% of Kel-F oil No. 10 on Chromosorb T. Prior to analysis the column was conditioned with fluorine and chlorine trifluoride in order to remove moisture and reactive organic compounds. The thermal conductivity detector was equipped with nickel-coated filaments resistant to corrosion with metal fluorides. Fig. 5.34 illustrates the analysis of tungsten, rhenium and osmium fluorides by this method. 

The current literature is replete with accounts of the determination of one fatty acid or another in numerous natural samples. It seems that the most common way to render fatty acids amenable to GC analysis is to use the time-honored method of acid-catalyzed direct esterification. The traditional acid catalysts H2SO4 and HCl are still used, but one also notes considerable reference to boron trifluoride and trichloride for BFj, in particular, the shorter time (relative to the mineral acids) needed to effect complete esterification has been noted [207]. 

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