Gaseous boroxine: Mechanism of reaction with boron trihalides

Article abstract of DOI:10.1021/ic50052a027

Low-pressure reactions of gaseous boroxine (H₃B₃O₃) with boron trihalides to produce dihaloborane and boric oxide have been studied by infrared absorption techniques. Kinetic data indicate that the reaction is close to first order in boroxine pressure. The pressure dependence of BF₃ in the BF₃-H₃B₃O₃ reaction is close to zero order for BF₃ pressures above 10 mm but tends toward a higher order at lower pressures. Reactions are accelerated in cells coated with B₂O₃(s). Reaction rates increase in the order BF₃ < BCl₃ < BBr₃. Spectra of products of the reaction of ¹⁰B-labeled compounds show that the boron atoms in H₃B₃O₃ appear in HBX₂ and the boron atom in BX₃ appears in B₂O₃(s). A surface mechanism which accounts for the ¹⁰B distribution in the products is proposed.