Levorotatory and dextrorotatory enantiomers of 1-phenylmethyl-4-sulfonylpiperazine of the formula 1their preparation and use for the preparation of substantially optically pure enantiomers of 1-phenylmethylpiperazine, which are themselves valuable intermediate products for the preparation of optically active therapeutic compounds having a very high degree of optical purity. The target therapy delivery site, an electrode combination, or both, may be selected based on the changes in brain activity. The polymer has urea linkages formed from the imine and polyisocyanate and urethane linkages formed from the hydroxyl group and the polyisocyanate.