Terpene

Terpenes are a class of hydrocarbons, produced by many plants, particularly conifers. They are major components of resin, and of turpentine produced from resin. The name "terpene" comes from "turpentine".

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Terpenes are derived from isoprene C5H8 units and have the basic formula of multiples of it, i.e., (C5H8)n. This is called the isoprene rule. The isoprene units can be arranged in a linear way or forming rings.

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One can consider isoprene as one of nature's preferred building blocks.

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Terpenes can be classified according to the number of isoprene units that they contain:

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• Monoterpenes, C₁₀H₁₆, 2 isoprene units
• Sesquiterpenes, C₁₅H₂₄, 3 isoprene units
• Diterpenes, C₂₀H₃₂, 4 isoprene units
• Triterpenes, C₃₀H₄₈, 6 isoprene units
• Tetraterpenes, C₄₀H₆₀, 8 isoprene units
• Polyterpenes with a large number of isoprene units

The important plant photosynthetic pigment carotene is a tetraterpene. Rubber is essentially a polyterpene.

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Most plant essential oils consist of such important terpenes as:

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• alpha-Pinene (pine oil up to 40%)
• beta-Pinene (in some type of pine oils (turpentine) and minor component of many other essential oils)
• delta-3-Carene (in pine oil up to 40%)
• Limonene (in citrus oil).

If terpenes are further modified, for instance by adding hydroxyl groups or moving or removing a methyl group, the resulting compounds are called terpenoids, e.g. menthol and thujone. (Some authors also call these compounds terpenes.)

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Plant: Land plants (embryophytes)Non-vascular plants (bryophytes)Hepaticophyta - liverwortsAnthocerotophyta - hornwortsBryophyta - mossesVascular plants (tracheophytes)Lycopodiophyta - clubmossesEquisetophyta - horsetailsPteridophyta - "true" fernsPsilotophyta - whisk fernsOphioglossophyta - adderstonguesS...

Conifers: redirect Pinophyta...

Resin: :This article is about the chemical secretion. For other meanings of resin, see the disambiguation page...