Isoprene (2-methyl-1.3-butadiene) is a common organic compound with the formula CH2=C(CH3)CH=CH2 and is used mainly to make synthetic rubber. Under standard conditions it is a colourless liquid. However, this compound is highly volatile because of its low boiling point. Isoprene is the monomer found in natural rubber and is also a common structure in a wide variety of other natural compounds, collectively termed terpenoids. Isoprene is a useful building block for various chemicals and intermediates.