Octane is a straight-chain alkane with the chemical formula CH3(CH2)6CH3. Octane has 18 structural isomers (25 including stereoisomers): Octane (n-octane) 2-Methylheptane 3-Methylheptane (2 enantiomers) 4-Methylheptane 3-Ethylhexane 2,2-Dimethylhexane 2,3-Dimethylhexane (2 enantiomers) 2,4-Dimethylhexane (2 enantiomers) 2,5-Dimethylhexane 3,3-Dimethylhexane 3,4-Dimethylhexane (2 enantiomers + 1 meso compound) 3-Ethyl-2-methylpentane (2 enantiomers) 3-Ethyl-3-methylpentane 2,2,3-Trimethylpentane… (More on Octane)