Properties of Boron

Crystalline form cubic (similar to diamond) Lattice parameters a, = 5.4307 nm 

The hydrogen reduction of the chloride is the major production processPlPl with a deposition reaction is as follows  

The deposition temperature range is 900-1300°C and the pressure is up to 1 atm. The kinetics of this reaction were studied by Tanaka.t i This reaction is used to produce boron fiberson an industrial scale (see Ch. 19). 

Boron is also obtained by the pyrolysis of diborane. Only moderate temperature is required (400-900°C) with a pressure up to 1 atm [6][7] 

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The BF4 ion has a regular tetrahedral configuration. The most important property of boron trifluoride is its great capacity to act as an electron pair acceptor (Lewis acid). Some examples of adducts are ... 

Nakamura, K., Preparation and Properties of Boron Nitride Films by Metal Organic Chemical Vapor Deposition, /. Electochem. Soc., 133-6 120-1123 (1986)... 

Elements dissolved in boron influence its crystal structure. Dissolved impurities also influenee the physical and chemical properties of boron, especially the electrical properties, because boron is a semiconductor. Preparation of solid solutions in jS-rh boron requires a careful choice of crucible material. To avoid contamination, boron nitride or a cold, coinage-metal crucible should be used or the levitation or floating-zone melting techniques applied. 

Recently, several reports of the flame-retardant properties of boron-containing bisphenol-A resins have appeared from Gao and Liu.89 The synthesis of a boron-containing bisphenol-A formaldehyde resin (64 and 65) (Fig. 42) from a mixture of bisphenol-A, formaldehyde, and boric acid, in the mole ratio 1 2.4 0.5, has been reported.893 The kinetics of the thermal degradation and thermal stability of the resins were determined by thermal analysis. The analysis revealed that the resin had higher heat resistance and oxidative resistance than most common phenol-formaldehyde resins. 

There are a number of papers in the open literature explicitly reporting on the properties of boron cluster compounds for potential neutron capture applications.1 Such applications make full use of the 10B isotope and its relatively high thermal neutron capture cross section of 3.840 X 10 28 m2 (barns). Composites of natural rubber incorporating 10B-enriched boron carbide filler have been investigated by Gwaily et al. as thermal neutron radiation shields.29 Their studies show that thermal neutron attenuation properties increased with boron carbide content to a critical concentration, after which there was no further change. 

Diorganoboryloxides, R2BO, bearing bulky organic substituents are quasi-alkoxide ligands for main group and transition metals. Because of the 7r-acceptor properties of boron, these anions are weaker 7r-donors than alkoxides, and this is reflected in their structural chemistry. Diethylzinc reacted with the borinic anhydride (9-BBN)20, Scheme 82, to afford the alkylzincboryloxide [EtZnO(9-BBN)]4 129, which also crystallizes in heterocubic form.187... 

Boron remarks on its crystal structure. The atomic and physical properties of boron are reported in 5.13.2 with a few data about its crystal structures in the elemental state. A few more comments will be added here in order to insert also boron in this short summary of the crystal properties of the various elements. In this general although partial picture, the peculiar characteristics of boron have indeed to be underlined. 

B. Mortazavi, S. Ahzi, Molecular dynamics study on the thermal conductivity and mechanical properties of boron doped graphene., Solid State Communications, vol. 152, pp. 1503-1507, 2012. 

H. Nakazawa, A. Sudoh, M. Suemitsu, K. Yasui, T. ltoh,T. Endoh, Y. Narita, M. Mashita, Mechanical and tribological properties of boron, nitrogen-coincorporated diamond-like carbon films prepared by reactive radio-frequency magnetron sputtering., Diamond and Related Materials, vol. 19, pp. 503-506, 2010. 

This contribution first surveys some of the attractive properties of boron, briefly describing applications that have been developed mostly with non-aromatic boron-containing compounds. It then examines many of the stable, formally aromatic boron heterocycles that have been reported to dale, covering much of the pertinent literature through the end of 1999. With the sum of these two parts, I hope the reader will gain an appreciation of the untapped potential held by boron heterocycles, especially for constructing new bioactive agents. 

These reagents demonstrate two important properties of boron and aluminium compounds. Xf you are uncertain of tbe periodic table just check to see where these two elements come. Neutral tervalent B and Al compound are electron deficient ... 

Zeolites (3 were treated with a NaBO, solution, and the porous properties of boronated samples were investigated by sorption measurements with benzene and nitrogen as adsorbate, TEM, SEM and composition analysis. It is shown that the micropores are converted into the mesopores and the mesopores are developed into larger mesopores due to the extraction of framework silicon by base. The small atom size of boron and the poor stability of boron in framework should be responsible for the silicon removal in a large amount. The dissolution of silicon also causes the corrosion of outer surface of particles and the decrease of particle size. 

List three ways in which the properties of boron differ from those of the other group 3A elements. 

It is not necessary to dwell on the properties of boron that make it attractive, especially in prepreg tape form, for both filament-wound and laid-up structures. Table III compares boron with both S-glass and Thomel 5-S in epoxy composite form. The numbers shown are typical for uniaxial specimens at about 60 vol % fiber. Specific points worthy of mention for their merit, or lack thereof, are... 

Ingles TA, Popper P (1960) The preparation and properties of boron nitride. In Popper P (ed) Special Ceramics. Heywood and Comp, London, p 144... 

The uniqueness of structure and properties of boron is a consequence of its electronic configuration. The small number of valence electrons (three) available for covalent bond formation leads to electron deficiency, which has a dominant effect on boron chemistry. 

Paushkin and Topchiev also used H3P()4-BF3 at room temperature to alkylate benzene with olefins (287,402). For alkylation of benzene with alcohols, temperatures of 90-97° and a feed mole ratio of 0.5 alcohol 1.0 benzene 0.5 catalyst were recommended (394). In a recent study (400a) these authors supplemented their previously published views (396) concerning the properties of boron fluoride complexes with phosphoric acid, alcohols, and sulfuric acid as catalysts. Data on the electroconductivity of these catalysts was correlated with their activity in alkylation of isobutane and it was concluded (400a) that the acid ion concentration did not affect the alkylation or polymerization reactions over these catalysts, and therefore the carbonium ion mechanism was not applicable. 

Deguchi, M., Kitabatake, M. and Hirao, T. (1996), Electrical properties of boron-doped diamond films prepared by microwave plasma chemical vapour deposition. Thin Solid Films,... 

L. Pauling and Z. S. Herman, The unsynchronized-resonating-covalent-bond theory of the structure and properties of boron and the boranes. in Advances in Boron and the Boranes, J. F. Liebman, A. Greenberg, and R. E. Williams, eds., VCH Publishers, New York, 1988, pp. 517-529. 

For some properties of boronates of glycosides, nucleosides, and related compounds, see Tables IV, VI, and VII. 

The following Tables record some physical properties of boronates of sugars, glycosides, C- and N-glycosyl compounds including nucleosides, alditols, and anhydro sugars. 

This process achieves the extraction of m-xylene by means of HF—BFj. It exploits the complexing properties of boron trifluoride on. aromatic compounds, and the particular ability of m-xylene to fonn the most stable complex. Subsequently, this isomer, added to a mixture of Cg aromatics which does not conCrin it, displaces the other components from their respective complexes, and the composition of the medium depends on the values of the equilibrium constants, or m-xylene, 2 for o-xylene, 0.14... 

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