Preparation of t-Butyldimethylphosphine Borane and t-Butyldiethylphosphine Borane by Selective Grignard Reagent Substitution of Phosphorus Trichloride

Abstract

The synthesis of differentially substituted trialkylphosphine boranes from the selective substitution reaction of Grignard reagents with phosphorus trichloride in a single reaction flask was studied. The reaction temperature, stoichiometric loading of the first equivalent of Grignard reagent and reaction time were found to be important for maximizing the yield and selectivity of the reaction. Reaction conditions were optimized to achieve maximum yield of t-butyldiethylphosphine borane. The optimized conditions were applied to the syntheses of t-butyldiethylphosphine borane and t-butyldimethylphosphine borane, which provided 60% and 62% isolated yields respectively. Products were characterized with mass spectrometry, infrared spectroscopy, 1H, 13C, and 31P nuclear magnetic resonance spectroscopy. KEYWORDS: Synthesis; Trialkylphosphine; Grignard Reagent; Selective; Substitution Reaction; t-Butyldiethylphosphine Borane; t-Butyldimethylphosphine Borane; Phosphorus Trichloride