Some science behind the scenes

Monoterpene

Terpenes are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, and by some insects.  They often have a strong odour and may protect the plants that produce them by deterring herbivores and by attracting predators and parasites of herbivores.  Terpenes are hydrocarbons.

Although sometimes used interchangeably with "terpenes", terpenoids are modified terpene as they contain additional functional groups, usually oxygen-containing.  Vitamin A is a terpenoid.

Terpenes and terpenoids are the primary constituents of the essential oils of many types of medicinal plants and flowers. Essential oils are used widely as fragrances in perfumery, and in medicine and aromatherapy.

Monoterpenes

are a class of terpenes that consist of two isoprene units and have the molecular formula C10H16.

  • Acyclic - Ocimene, Myrcenes
  • Monocyclic - Limonene, Terpinene,  Phellandrene,  Umbellulone
  • Bicyclic - Pinene (β and α, Camphene, Thujene, Sabinene, Carene
     

Monoterpenoid

Menthol plus a number of other substances on the other hand are classed as a monoterpenoid, not a true terpene.

  • Acyclic - Linalool, Citronellal, Citral, Citronellol, Geraniol Geranyl pyrophosphate
  • Monocyclic - Grapefruit mercaptan, menthol, p-Cymene, thymol, Perillyl alcohol, Carvacrol
  • Bicyclic - Camphor, Borneol, Eucalyptol, Halomon, Eucalyptol, Pinene, Ascaridole
     

Monoterpenes are emitted by forests and form aerosols that are proposed to serve as cloud condensation nuclei (CCN).

Such aerosols can increase the brightness of clouds and cool the climate.  

Several monoterpenes derivatives have antibacterial activity, such as linalool.

Observations

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