benzyl amine benzphetamine and a methyl amine methamphetamine is quite large that is the k b of benzphetamine is about 1 20 th of the k b of methamphetamine it has further been discovered that concentration of benzphetamine in an organic solvent is approximately 70 to 700 times greater than its solubility in water thus a nearly complete separation of benzphetamine can be accomplished by solvent extraction because methamphetamine hydrochloride does not partition in the organic solvent such as toluene in accordance with this invention crude benzphetamine hydrochloride is added to a vessel containing both an organic solvent and water while stirring vigorously the ph of the water phase is adjusted to the range of from about 6 0 to about 8 0 by the addition of a suitable acid or base at such ph range the benzphetamine hydrochloride is converted to a base and methamphetamine is converted to an acid salt vigorous agitation of the mixture assures adequate contact of both phases with the crude benzphetamine base containing methamphetamine contaminant upon contact the benzphetamine partitions into the organic phase and the methamphetamine hydrochloride partitions into the aqueous phase this operation is performed at ambient temperature and pressure the only equipment required is a suitable vessel and an adequate stirrer optionally the process of this invention can be carried out in the reactor in which the benzphetamine hydrochloride is produced alternatively this process works in the opposite direction a mixture of methamphetamine base and benzphetamine base that is dissolved.