A classic case of the different effects of enantiomers on chiral environments is the different odors exhibited by some enantiomeric pairs.Odors are detected by the olfactory sensors in the nose and these sensors are believed to contain specific chemical receptor sites.The receptor sites are specific configurations of compounds with which volatile odiferous compounds interact.The receptor sites are believed to be chiral; so one enantiomer of an odiferous compound “fits” that particular site and therefore produces a chemical Interaction that is then transferred by the nervous system to the brain.The enantiomer with the opposite configuration does not fit that particular site, but may fit another receptor site and produce a different odor sensation.The odor exhibited by spearmint oil is caused by the monoterpene compound R-(-)-carvone.Its enantiomer is S-(+)-carvone, which is found in caraway seed oil.Very different odors are produced by olfactory interaction with these two enantiomeric but otherwise identical terpenes.Another example from the same monoterpenes (C10 compounds) is the pair of hydroxyaldehydes known as the citronellasThe two hydroxyl dihydrocitronellals exhibit different odors: a mint odor from the (R)-(+) enantiomer and a lily-of-the-valley odor from the (S)-(-) enantiomer.