There are 18 isomers of octane which are n-octane, 2-methylheptane, 3-methylheptane, 4-methylheptane, 2.2-dimethylhexane, 2.3-dimethylhexane, 2.4-dimethylhexane, 2.5-dimethylexane, 3.3-dimethylhexane, 3.4-dimethylhexane, 3-ethylhexane, 2.2.3-trimethylpentane, 2.2.4-trimethylpentane, 2.3.3-trimethylpentane, 2.3.4-trimethylpentane, 2-methyl-3-ethylpentane, 3-methyl-3-ethylpentane and tetramethylbutane. The chemical formula for Octane is C8H18.
Octane is an alkane. It has 18 structural isomers as seen above. The most important isomer of this group is the 2.2.4-trimethylpentane (known as isooctane) because it is used as a reference value in the octane rating scale. Isooctane, the 2.2.4-trimethyplentane isomer, is a part of gasoline and it helps to reduce the engine knocking noise vehicles sometimes have.
Octane's 18 isomers all have melting and boiling points.
- N-Octane has a melting point of -57 degrees Celsius and a boiling point of 126 C.
- 2-methylheptane has a melting point of -109 C and a boiling point of 118 C.
- 3-methylheptane has a melting point of -121 C and a boiling point of 119 C.
- 4-methylheptane has a melting point of -121 C and a boiling point of 118 C.
- 3-ethylhexane has a boiling point of 119 C.
- 2.2-dimethylhexane has a melting point of -121 C and a boiling point of 107 C.
- 2.3-dimethylhexane has a melting point of -110 C and a boiling point of 116 C.