Synthesis by use of molecular carbon. Part I. Boron halides

Abstract

Carbon vapour generated from a carbon arc has been co-condensed with various boron halides. In this manner diboron tetrachloride afforded a mixture of C(BCl₂)₄, ClC(BCl₂)₃, and Cl₂C(BCl₂)₂; and boron trichloride yielded the last two compounds as well as Cl(Cl₂B)C:C(BCl₂)Cl. Diboron tetrafluoride and carbon vapour reacted to give species derived from C₁, C₂ and C₃ molecules, viz., (F₂B)₄C, (F₂B)₂C:C(BF₂)₂, and (F₂B)₂C:C:C(BF₂)₂. However, tetrakis(difluoroboryl)methane was only isolated in small amount and identified mass spectrometrically. The principal boron-containing compound obtained from the reaction between methylboron dichloride and carbon vapour was Me₂C(BCl₂)₂. Acetylene was the main non-boron-containing product identified. Non-boron-containing products, (ethylene, acetylene, and diacetylene) predominated when trimethylboron was used, but tetramethyldiborane was also formed. The nature of the reactions is discussed.