Boranes technique

The borane technique, described earlier for In203 preparation, was also used to deposit ZnO on Sn/Pd-activated glass using a solution of Zn(N03)2 and dimethylamine borane at 50°C [59], The films were randomly oriented polycrys-talhne ZnO, and the crystals were hexagonal shaped, with a typical size of 0.2 jim, at moderately high dimethylamine borane concentrations at low concentrations, the grains were smaller and more irregular. 

Synthesis depends on gas-phase pyrolysis techniques , and interconversion is by electrochemical oxidation . Understanding of the mechanisms by which the boranes interconvert and build up into larger clusters is growing . 

The field of transition metal-catalyzed hydroboration has developed enormously over the last 20 years and is now one of the most powerful techniques for the transformation of C=C and C=C bonds.1-3 While hydroboration is possible in the absence of a metal catalyst, some of the more common borane reagents attached to heteroatom groups (e.g., catecholborane or HBcat, (1)) react only very slowly at room temperature (Scheme 1) addition of a metal catalyst M] accelerates the reaction. In addition, the ability to manipulate [M] through the judicious choice of ligands (both achiral and chiral) allows the regio-, chemo-, and enantioselectivity to be directed. 

Techniques for handling air-sensitive compounds are reviewed in Brown, H. C. Kramer, G. W. Levy, A. B. Midland, M. M. "Organic Syntheses via Boranes" Wiley New York, 1975 Technical data on air-sensitive compounds is also available in Lane, C. F. Kramer, G. W. Aldrichemica Acta 1977, 10, 11-16. 

Matrix isolation spectroscopy is a powerful technique for identifying unstable products of photodissociation reactions. The small number of boron compounds investigated by this procedure include trioxaborolane, amine-borane and borazine. 

All of the following manipulations are performed under argon using standard Schlenk techniques. Solvents are degassed and distilled under nitrogen immediately before use unless otherwise noted. (Cp RuCl2)2 is available from Strem Chemicals, Inc., and is used as received. Lithium borohydride, LiBEU (2.0 M in tetrahydrofuran), and borane tetrahydrofuran, BH3 THF (1.0 M in tetrahydro-furan), are available from Aldrich Chemical Co. and are used as received. Note that these solutions decrease in molarity depending on time and use, and, if solutions are not titrated before use, appropriate increases in the volumes of solution used may be required. 

For fuller discussion, see Sanderson VdcMiizw Manipulation of Volatile Compounds John Wiley and Sons Ltd, NY, 1948 L.W.Muller Vacuum Technology Principles and Applications, Chapman Hall Ltd, 1995 W.H.Kohl Handbook of Materials Techniques for Vacuum Devices, American Institute of Physics Press, 1994 Shriver The Manipulation of Air-sensitive Compounds McGraw-Hill Book Co, NY, 1969 Brown Organic Syntheses via Boranes, Wiley, NY, 1975 A.Pelter Borane Reagents, Academic Press Inc., 1988. 

Pyridine borane [110-51-0] can be prepared using benchtop techniques via... 

Borazine has been known since the pioneering work of Alfred Stock early in this century. Stock s work was important in two regards He was the first to study compounds such as the boranes. silanes, and other similar nonmetal compounds, and he perfected vacuum line techniques for the handling of au- and moisture-sensitive compounds, invaluable to the modern inorganic chemist.67 Stock synthesized borazine by heating the adduct of diborane and ammonia 66... 

Brown, H. C., 1973, Organic Syntheses via Boranes. Wiley-Interscience, New York. See Chapter 9, p. 191, Laboratory Operations with Air-Sensitive Substances," by G. W. Kramer, A. B. Levy, and M. M. Midland, which stresses syringe techniques. 

An alternative technique (which uses essentially the same apparatus assembly as described above) involves passage of borane directly into a solution of the organic substrate in tetrahydrofuran, diglyme or ether to effect immediate... 

Controlled radical polymerization (CRP) is an attractive tool, because of the resultant controllability of polymerization, and because of it being a versatile method to synthesize of well-defined polymer hybrids. The three main radical polymerization techniques, ATRP, NMP, and RAFT polymerization, have thus been employed. Other techniques, such as the oxidation of borane groups, have also been studied. In general, using CRP techniques, block copolymers can be synthesized from terminally functionalized PO as PO macroinitiator, and block copolymers can be prepared from functionalized PO produced by the copolymerization of olefins with functional monomers. 

Bis(dimethylamino)borane may be prepared by the reduction of CIB[N(CH3)2]21 or by gas-phase exchange of hydride and dimethylamino groups on boron.2,3 The latter method, using diborane(6) and excess B[N(CH3)2]3 and described here, is the most convenient for the synthesis of a few millimoles of product. The basic vacuum-line techniques necessary to carry out this synthesis are detailed in reference 4. 

The compound bis-/i-(dimethylamino)-diborane(6), [(CH3)2NBH2]2, has been prepared by the pyrolysis of dimethylamine-borane, (CH3)2NH BH3,1-3 and by a novel iodination-deprotonation of (CH3)2NH BH3,4 The gas-phase pyrolysis described here is the simplest and most convenient method for the preparation of small samples, since no solvent is involved and separation problems are thus minimized. The basic vacuum-line techniques necessary for this synthesis are outlined in reference 7. 

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