Editing Cetane number (section)

== Chemical relevance ==
[[Cetane]] is the hydrocarbon with chemical formulas C<sub>16</sub>H<sub>34</sub> and specifically the structural formula CH<sub>3</sub>(CH<sub>2</sub>)<sub>14</sub>CH<sub>3</sub>. Also named n-hexadecane, it is an unbranched [[Saturated and unsaturated compounds|saturated]] [[alkane]]. Cetane ignites with a short delay under compression, and is assigned a cetane number of 100. [[alpha-methyl naphthalene|Alpha-methylnaphthalene]], which has a long delay period, was assigned a cetane number of 0, but has been replaced as a reference fuel by [[Isocetane|2,3,4,5,6,7,8-heptamethylnonane]], which is assigned a cetane number of 15.<ref name=":0">{{Cite book|last=Speight|first=James G.|url=http://doi.wiley.com/10.1002/9781118986370|title=Handbook of Petroleum Product Analysis: Speight/Handbook of Petroleum Product Analysis|date=2014-12-12|publisher=John Wiley & Sons, Inc|isbn=978-1-118-98637-0|location=Hoboken, NJ|language=en|doi=10.1002/9781118986370}}</ref> All other [[hydrocarbon]]s in diesel fuel are indexed to cetane as to how rapidly they ignite under compression, i.e. [[diesel engine]] conditions. Since hundreds of components comprise diesel fuel, the overall cetane number of that fuel is the average cetane quality of all the components. High-cetane components have a disproportionate influence, hence the use of high-cetane additives.