sesquiterpene

… The hydrocarbon C ₁₀ H ₁₆ with n = 2 is called monoterpene, and since the main components of essential oils are monoterpenes and their hydrogen-containing derivatives, the term terpene in the narrow sense refers to monoterpene. Terpenes with n = 3 or more are also known in nature, and n = 3 is called sesquiterpene, n = 4 is called diterpene, n = 5 is called sesterterpene, and n = 6 is called triterpene. When n ≧ 8, it is sometimes called polyterpene, and isoprene itself is thought to belong to the hemiterpene with n = 1. …

*Some of the terminology explanations that mention "sesquiterpene" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…　n＝2にあたる炭化水素C₁₀H₁₆はモノテルペンmonoterpeneと呼ばれ，精油の主成分はこのモノテルペンおよびその含水素誘導体であるため，狭義のテルペンといえばモノテルペンをさす。天然にはnが3以上のテルペンも知られており，n＝3をセスキテルペンsesquiterpene,n＝4をジテルペンditerpene,n＝5をセスタテルペンsesterterpene,n＝6をトリテルペンtriterpeneなどと呼ぶ。n≧8の場合をポリテルペンpolyterpeneと呼ぶことがあり，またイソプレン自身はn＝1のヘミテルペンhemiterpeneに属すると考えられる。…

※「sesquiterpene」について言及している用語解説の一部を掲載しています。

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