The reaction of mono- and dimethylamines with phosphorus trifluoride borane

Article abstract of DOI:10.1021/ic50025a034

The reaction between F₃PBH₃ and CH₃NH₂ gives [CH₃NH]F₂PBH₃, [CH₃NH]₂FPBH₃, or [CH₃NH]₃PBH₃ depending upon the experimental conditions used. In no case was CH₃NH₂BH₃ ever detected as a product of the methylamine reaction. On the other hand the reaction between F₃PBH₃ and (CH₃)₂NH gave good yields of (CH₃)₂NHBH₃ under conditions comparable to those used for methylamine, and gave [(CH₃)₂N]F₂PBH₃ or [(CH₃)₂N]₂FPBH₃ under more severe conditions. Displacement reactions provide a basis for listing the above bases in order of increasing base strength using BH₃ as a reference acid. The order is: F₃P < (CH₃NH)F₂P, [(CH₃)₂N]F₂P < N(CH₃)₃, NH(CH₃)₂ < (CH₃NH)₂FP, [(CH₃)₂N]₂FP. The results are discussed.