C5H8

thumb|upright=1.5|Constitution formula for isomers of C5H8 with CAS numbers The molecular formula C5H8 may refer to any of the following hydrocarbons: Pentynes: 1-Pentyne 2-Pentyne 3-Methyl-1-butyne or isopentyne, CAS 598-23-2 Pentadienes: 1,2-Pentadiene, two cis-z isomers, CAS 591-95-7 1,3 Pentadiene, CAS 504-60-9 (racemic mixture) cis-1,3-Pentadiene or (Z)-1,3-pentadiene, CAS 1574-41-0 trans-1,3-Pentadiene or (E)-1,3-pentadiene, or Piperylene 1,4-Pentadiene, CAS 591-93-5 2,3-Pentadiene, two axial isomers, CAS 591-96-8 (racemic mixture) (Ra)-2,3-Pentadiene, CAS 20431-56-5 (Sa)-2,3-Pentadiene, CAS 23190-25-2 Butadiene derivatives: 3-Methyl-1,2-butadiene, CAS 598-25-4 2-Methyl-1,3-butadiene or isoprene Cyclopentene Cyclobutane derivatives: Methylenecyclobutane, CAS 1120-56-5 Cyclobutene derivatives: 1-Methylcyclobutene, CAS 1489-60-7 3-Methylcyclobutene, CAS 1120-55-4 (racemic mixture) (R)-3-Methylcyclobutene, CAS 20476-28-2 (S)-3-Methylcyclobutene, CAS 30334-81-7 Cyclopropane derivatives: Ethenylcyclopropane or Vinylcyclopropane Ethylidenecyclopropane, CAS 18631-83-9 2-Methyl-1-methylenecyclopropane, CAS 18631-84-0 (racemic mixture) (R)-2-Methyl-1-methylenecyclopropane (S)-2-Methyl-1-methylenecyclopropane Cyclopropene derivatives: 1-Ethylcyclopropene, CAS 34189-00-9 3-Ethylcyclopropene, CAS 203442-62-0 1,2-Dimethylcyclopropene, CAS 14309-32-1 1,3-Dimethylcyclopropene, CAS 82190-83-8 (racemic) (R)-1,3-Dimethylcyclopropene (S)-1,3-Dimethylcyclopropene 3,3-Dimethylcyclopropene, CAS 3907-06-0 Bicyclopentane [[Bicyclo(1.1.1)pentane|Bicyclo[1.1.1]pentane]], CAS 311-75-1 Bicyclo[2.1.0]pentane or housane, CAS 185-94-4 Spiro[2.2]pentane or spiropentane, CAS 157-40-4

==Functional groups== The formula may also represent a monovalent functional group derived from any hydrocarbon with formula by removal of one hydrogen atom; or a divalent group derived from minus two hydrogens; and so on.