Pentene refers to all the alkenes with chemical formula C5H10 containing a single double bond within its molecular structure. 1-Pentene (pent-1-ene) and 2-pentene (pent-2-ene) differ by the location of the double bond at the first or second carbon-carbon bond. 1-Pentene is an alpha-olefin. Most often 1-pentene is made as a byproduct of catalytic or thermal cracking of petroleum, or during production of ethylene and propylene via thermal cracking of hydrocarbon fractions. 1-Pentene is rarely isolated as a separate compound. Instead, it is most often blended into gasoline or, in a mixture with other hydrocarbons, alkylated with isobutane to make gasoline.