Trichloride, boron reaction with diborane

Reaction with diborane and other boron hydrides yield boron trichloride ... 

Chloroboranes are another class of heteroatom-substituted boranes. Dichloroborane (CI2BH) and mono-chloroborane (CIBH2) are formed by the reaction of diborane with varying proportions of boron trichloride etherate (BCl3 OEt2). In ether solvents, both reagents are formed as the etherate.23 An alternative synthesis was the reaction of HCl with borane THF,24 but reduction of boron trichloride with lithium borohydride in ether proved to be the most useful route.23... 

The reaction with boron trichloride is unsatisfactory. Even in solution it is sluggish, so that little diborane is formed, and cleavage of the solvent may be severe, as in the case of monoglyme (200). It must therefore be concluded that CaH2 is very much less reactive for this purpose than LiH or NaH, and, in the absence of experimental evidence, we would expect the same to be true for SrH2 and BaH2. 

Arylboronic and arylborinic acids have been produced from the hydrolysis of intermediates in the reactions of aryl-tin and aryl-lead compounds with diborane. The preparation of di[bis(trimethylsilyl)methyl]chloroborane from the reaction of bis(trimethylsilyl)methyl-lithium and boron trichloride has been published. A new reagent for O-ethylboranediylation, ethylbis-(2-isopropyl-6-methyl-4-pyrimidinyloxy)borane (3) has been synthesized and used to prepare O-ethyl-boranediyl derivatives of alcohols, phenols, alkanediols, D-mannitol, and l-arabinose. Borane-methyl sulphide reportedly reacts smoothly with primary, secondary, and tertiary alcohols and phenols to provide a general and convenient synthesis of borate esters. ... 

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... 

Diborane is prepared by the reaction of sodium borohydride with iodine or boron trifluoride or trichloride in diglyme ... 

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. 

An excellent in situ preparation of diborane results from the reaction of boron trichloride (BCI3) or boron trifluoride (BF3) with sodium borohydride in the presence of alkenes, as shown above. This reagent gave virtually instantaneous conversion of an alkene to a trialkylborane at ambient temperatures, when done in a ether solvent. When diborane was isolated and purified it also reacted with alkenes, rapidly and quantitatively in ether solvents. 

The source of the boron is conveniently a boron halide or an ester of boric acid. Initial experiments were carried out by Finholt, Bond, and Schlesinger (107), who formed diborane by reacting boron trichloride with lithium aluminum hydride in ether solution at low temperatures (at which, apparently, the ether is not appreciably cleaved by the boron trichloride) and reported a 99.4% yield. This is historically the first reaction discovered to give essentially quantitative yields of diborane... 

The deposition of boron phosphide by CVD was carried out in a gas flow system by the thermal decomposition of diborane-phosphine mixtures in a hydrogen atmosphere and the thermal reduction of boron tribromide-phosphorus trichloride mixtures with hydrogen (37). The hydrides are thermodynamically unstable at room temperature and decompose rapidly at above 500°C, which tends to promote homogeneous nucleation by pyrolysis in the gas phase. The halides are thermally more stable than the hydrides, and higher substrate temperatures may be used in the thermal reduction process with essentially no gas-phase reactions. At high substrate temperatures, a phosphorus pressure equal to or greater than the vapor pressure of boron phosphide must be present over the substrate surface to maintain the stoichiometry of the deposit. 

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