room temperature and is complete in from about 15 to about 60 minutes with stirring the two resultant phases are distinct and easily separated the organic phase which contains sodium tetrakis pentafluorophenyl borate or potassium tetrakis pentafluorophenyl borate is separated from the aqueous phase solvent is then removed in such a way as to provide substantially ether free sodium tetrakis pentafluorophenyl borate or potassium tetrakis pentafluorophenyl borate it is understood that the term u201c substantially ether free u201d refers to an ether content in the salt of less than about 5 0 weight percent preferably less than about 3 0 weight percent and more preferably less than about 1 0 weight percent in order to achieve this ether is removed by atmospheric distillation the head temperature during the distillation must be as close to the boiling point of the aromatic hydrocarbon as possible at atmospheric pressure before the ether distillation is considered complete for example when toluene is the aromatic hydrocarbon the further the head temperature is from the normal boiling point for toluene of 110 u00b0 c the higher will be the ether content in the borate salt to achieve an ether content in the borate salt of less than about 0 5 weight the head temperature during the distillation should not be less than about 109 u00b0 c surprisingly when treated similarly tetrakis pentafluorophenyl borate magnesium bromide is not rendered ether.