Terpene

Many terpenes are made from resin from conifer trees like this pine.

A terpene is a type of natural organic compound. They are hydrocarbons made of one or more isoprene repeating units. Non-hydrocarbon derivatives, especially those with oxygen, and hydrocarbons where hydrogen and methyl groups are added to terpenes, are called terpenoids.

Types

Terpenes are grouped by the number of isoprene units. The only hemiterpene is isoprene itself, but other types of terpene have many different isomers.

Group	Isoprene units	Formula	Example	Example structure
Hemiterpene	1	C5H8	Isoprene
Monoterpenes	2	C10H16	Camphene
			Limonene	File:(R)-Limonene skeletal horiz.svg
Sesquiterpenes	3	C15H24	Zingiberene
			Longfoliene
Diterpenes	4	C20H32	Cembrene A
			Taxadiene
Triterpenes	6	C30H48	Squalene
			Hopane
Tetraterpenes	8	C40H64 or C40Hx	Lycopene
			β-Carotene
Polyterpenes	More than 8	C5nH8n	cis-Polyisoprene (natural rubber)
			trans-Polyisoprene (gutta-percha)

The tetraterpenes often include more than just the exact formula C₄₀H₆₄, because many important molecules in biology have more or less hydrogen while keeping the overall tetraterpene structure.