Task: Translation
Input (Czech): (S) nebo (R) Enantiomer slou eniny obecn ho vzorce IA, ve kter m Alk znamen  alkylovou skupinu obsahuj c  1 a  3 atomy uhl ku, a adi n  s l s kyselinou t to slou eniny odvozen  od fyziologicky p°ijateln  kyseliny. Do rozsahu rovn   n le   i postupy p° pravy t chto slou enin. Tyto  (S) a (R) enantiomery maj  lep   analgetickou · innost v porovn n  s jejich racem ty.\
Output (English): In the present invention there is disclosed a piperazinyl compound (S) or (R) enantiomer of the general formula IA, in which Alk represents an alkyl group containing 1 to 3 carbon atoms, and acid addition salt of this compound derived from a physiologically acceptable acid. The invention relates also to processes for preparing such compounds. These (S) and (R) enantiomers exhibit better analgesic activity if compared with that of their racemates.