A general method for the fluorination of compounds containing boron-hydrogen bonds

A method for the fluorination of compounds containing horon-hydrogen bonds using anhydrous hydrogen fluoride as the fluorinating agent is described. Trimethylamine-borane and tertiary-butylamine-borane are fluorinated sequentially, forming the heretofore unknown amlne-monofluoroborane and the amine-difluoroborane and the known amine-trifluoroborane and ammonium-tetrafluoroborate. Preliminary results are also presented on the methylamine-borane and lithium borohydride systems. The formation of the new partially fluorinated amine-boranes is confirmed. Proton and boron-11 n.m.r. data are presented for all of the trlmethylamlne-borane and tertlary-butylamlne-borane adducts. In addition, fluorine-19 n.m.r. data are presented for the trimethylamine-borane adducts. This method for the fluorination of hydridic hydrogens on boron requires no special equipment. The reaction can be run In the air (with precautions against excess moisture, In some cases) on a scale greater than 200 millimoles giving yields of better than 80%.