The preparation and stability of alkyl dichloroboronites

Convenient Synthesis of W(⋮CR)X3(dme) Compounds from W(⋮CR)(OBut)3 Triple-Bond Metathesis Products

“…Although attempts to optimize these procedures are still in progress, we can initially note that use of fewer than 3 equiv of BX 3 is deleterious: treating W(CPh)(OBu t ) 3 with 2 equiv of BCl 3 under conditions otherwise identical to those above provides W(CPh)Cl 3 (dme) in 50% yield (vs 84% when 3 equiv are used), which precipitates from a yellow (on account of unreacted W(CPh)(OBu t ) 3 ) rather than colorless reaction mixture. The failure of the reaction to go to completion with 2 equiv of BCl 3 may be the result of the increased steric bulk and/or decreased Lewis acidity of the presumed B(OBu t ) 3 - x Cl x products of alkoxide/halide metathesis relative to those of BCl 3 or of the inherent instability of B(OBu t ) 3 - x Cl x compounds with respect to disproportionation and decomposition …”

Synthesis and characterization of new amorphous Si/B/N/C ceramics with increased carbon content through single-source precursors

“…It should be noticed that the chlorination step leads to an equilibrium, from which the product cannot be distilled off since trichloroborane has the lowest boiling point (b.p.). In order to shift the equilibrium reaction quantitatively towards the products, catalytic amounts of aluminum trichloride must be added, causing the present alkoxydichloroborane to decompose completely into boron trioxide, trichloroborane and an alkyl chloride [20,21] (Fig. 3c).…”

“…The length of the alkyl rest R′ in the alkoxy group determines both the stability of the alkoxydichlorobo- rane [20] and the b.p. of the intermediate organoborane dialkylester.…”

Rearrangement in Alkyl Groups during Substitution Reactions

“…The alkyl halide may, or may not, be rearranged, depending on the mechanism of the reaction. At 20', isomerically pure n-alkyl halides (n-Pr, nBu) are obtained from the dialkyl hydrogen phosphite complexes with boron trichloride (7), silicon tetrachloride (75), and titanium tetrachloride (53), from the trialkyl phosphate complexes with boron trichloride At higher temperatures, some rearrangement to secalkyl, and possibly t-alkyl groups, suggests that carbonium-ion intermediates may also be involved. Iso-…”