[{"from": "human", "value": "Please give me some details about this molecule. [C][C][C][C][C][C][C][C]"}, {"from": "gpt", "value": "The molecule is an alkane with the chemical formula C8H18. It has 18 isomers. One of the isomers, 2,2,4-trimethylpentane or isooctane, is of major importance, as it has been selected as the 100 point on the octane rating scale, with n-heptane as the zero point. Octane ratings are ratings used to represent the anti-knock performance of petroleum-based fuels (octane is less likely to prematurely combust under pressure than heptane), given as the percentage of 2,2,4-trimethylpentane in an 2,2,4-trimethylpentane / n-heptane mixture that would have the same performance. It is an important constituent of gasoline."}]