text: The chemical synthesis of tramadol is described in the literature. Tramadol  has two stereogenic centers at the cyclohexane ring. Thus,  may exist in four different configurational forms:
  * (1R,2R)-isomer
  * (1S,2S)-isomer
  * (1R,2S)-isomer
  * (1S,2R)-isomer
  The synthetic pathway leads to the racemate (1:1 mixture) of (1R,2R)-isomer and the (1S,2S)-isomer as the main products. Minor amounts of the racemic mixture of the (1R,2S)-isomer and the (1S,2R)-isomer are formed as well. The isolation of the (1R,2R)-isomer and the (1S,2S)-isomer from the diastereomeric minor racemate [(1R,2S)-isomer and (1S,2R)-isomer] is realized by the recrystallization of the hydrochlorides.
  The drug tramadol is a racemate of the hydrochlorides of the (1R,2R)-(+)- and the (1S,2S)-(−)-enantiomers.
  The resolution of the racemate [(1R,2R)-(+)-isomer / (1S,2S)-(−)-isomer] was described employing (R)-(−)- or (S)-(+)-mandelic acid. This process does not find industrial application, since tramadol is used as a racemate, despite known different physiological effects of the (1R,2R)- and (1S,2S)-isomers, because the racemate showed higher analgesic activity than either enantiomer in animals and in humans.