Cetane is the common name for n-hexadecane (C16H34), a straight-chain alkane with 16 carbon atoms. It is the reference compound used to measure the ignition quality of diesel fuel, giving rise to the term 'cetane number'. Pure cetane is assigned a cetane number of 100, and higher cetane numbers indicate better ignition characteristics. Heptadecane (C17), octadecane (C18) and nonadecane (C19) are different alkanes and are not called cetane.
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