gen ▁double ▁bond ▁in ▁the ▁ring . ▁This ▁path way ▁results ▁in ▁natural ▁con i ine ▁that ▁is ▁a ▁mixture — a ▁rac em ate — com posed ▁of ▁two ▁en anti om ers , ▁the ▁s tere ois om ers ▁( S )- ( + )- con i ine ▁and ▁( R )- ( − )- con i ine , ▁depending ▁on ▁the ▁direction ▁taken ▁by ▁the ▁chain ▁that ▁branches ▁from ▁the ▁ring . ▁Both ▁en anti om ers ▁are ▁to xic , ▁with ▁the ▁( R )- en anti omer ▁being ▁the ▁more ▁bi olog ically ▁active ▁and ▁to xic ▁of ▁the ▁two ▁in ▁general . ▁Con i ine ▁holds ▁a ▁place ▁in ▁organ ic ▁chem istry ▁history ▁as ▁being ▁the ▁first ▁of ▁the ▁important ▁class ▁of ▁al kal oid s ▁to ▁be ▁synth es ized , ▁by ▁Albert ▁L aden burg ▁in ▁ 1 8 8 6 , ▁and ▁it ▁has ▁been ▁synth es ized ▁in ▁the ▁labor atory ▁in ▁a ▁number ▁of ▁unique ▁ways ▁through ▁to ▁modern ▁times . ▁ ▁Hem lock ▁poison ing ▁has ▁been ▁a ▁periodic ▁human ▁concern , ▁a ▁regular ▁veter inary ▁concern , ▁and ▁has ▁had ▁significant ▁occurr ences ▁in ▁human ▁and ▁cultural ▁history . ▁Not ably , ▁in ▁ 3 9 9 ▁BC , ▁S ocr ates , ▁when ▁he ▁was ▁sent enced ▁to ▁death , ▁chose ▁to ▁die ▁by ▁drink ing ▁a ▁con i ine - cont aining ▁mixture ▁of ▁poison ▁hem lock . ▁ ▁Natural ▁orig ins ▁ ▁Po ison ▁hem lock