L1 /   
4
CH1012
TERPENES II
• Isoprene (2-methyl-1,3-butadiene) is emitted by plants (3 x 1011 kg /yr) into the atmosphere.
• Terpenes are not actually formed in plants from isoprene, but this is a useful way to simplify the examination of such structures.
• Monoterpenes have 2 isoprene units.
  Sesquiterpenes have 3 isoprene units.
tail
tail
tail
tail
http://www.leffingwell.com/chirality/limonene.htm – chiral isomers
(R)-( +)-limonene - fresh citrus, orange-like   (S)-(-)-limonene - harsh, turpentine-like, lemon note