| 摘要 |
A boron trihalide, with or without a dihaloborine, is prepared by reacting an oxygen-containing boron compound and a hydrogen halide in the presence of free or combined carbon. The reaction may be performed at 900-1400 DEG C., with residence times 0.01-60 sec. and hydrogen halide pressures 1-10 atmospheres. Subatmospheric pressure is also referred to. The boron compound may be boric oxide, metal or alkyl borate, or trihaloboroxine (B3O3Cl3), and hydrogen halides are HCl, HBr and Hl. The carbon may be mixed with the boron compound, in the proportion of at least one atom of carbon per atom of oxygen in the compound, but when an alkyl borate is used, may be the carbon in the alkyl group itself. The product gases containing boron trihalide with or without dihaloborine, hydrogen, carbon monoxide and excess hydrogen halide are cooled to 300 DEG C. in one sec. or less and may be separated by fractional distillation, absorption or adsorption, or, when hydrogen chloride is used, fractional condensation in three traps cooled respectively to -78 DEG C., -120 DEG C. and - 196 DEG C. The first trap contains BCl3 and some BHCl2, the second BCl3 and BHCl2, and the third HCl. Mixtures of BCl3 and BHCl2 may be refluxed in a fractionating column to produce BCl3 and B2H6 from the BHCl2. The trihaloboroxine may be prepared by preliminary reaction of BCl3 and B2O3 at 250-500 DEG C. |
