Preparation of high purity trimethylborane

Abstract

The preparation of high-purity trimethylborane is described. Impurities were removed by fractionation of the ammonia adduct, NH3: B(CH3)3. Mass pectrometric analyses were used during the fractionation to determine these impurities. After purification of the B(CH3)3 in the form of its ammonia adduct, high-purity hydrogen chloride was used to regenerate the B(CH3)3. This reaction and the subsequent distillation were carried out in a stainless steel system. Storage as a gas in stainless steel cylinders, rather than as a solid addition complex in glass vessels, eliminated the possibility of recontamination on regeneration. The purity of B(CH3)3 was determined cryoscopically to be 99.9 mole percent.