Cyclic monoterpenes, functional groups

Monoterpenes occur in plants in various structural forms some are cyclic while the others are acyclic. They also contain various types of functional group, and depending on their functional groups they can be classified as simple hydrocarbons, alcohols, ketones, aldehydes, acids or phenols. Some examples are cited below. 

Quite interesting and indicative in respect to the authentication of the compounds may also be their oxygen isotope characteristics. OH-groups of acyclic and of some mono-cyclic monoterpenes are introduced as OH" from water, substituting the pyrophosphate functionality of the biosynthetic precursor. This hydrolysis is probably accompanied by a kinetic isotope effect, from where a relative low 8 Q-value is to be expected. The 8 0-value of synthetic analogues will depend on the oxygen source... 

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