Chemical structure of decahydronaphthalene, a.k.a. <a href="https://en.wikipedia.org/wiki/Decalin" class="extiw" title="w:Decalin">Decalin</a>; carbons numbered according to different IUPAC numbering rules. <br><p>The <b>blue</b> numbers depict the IUPAC rules for numbering of <i>fused</i> polycyclic hydrocarbons. This nomenclature is <b>preferred</b> for polycylics consisting of at least two fused rings with a circumference of at least five atoms each (<a rel="nofollow" class="external text" href="https://old.iupac.org/reports/provisional/abstract04/BB-prs310305/Chapter2-Sec25.pdf">see here, p.90</a>). <br></p>
The <b>grey</b> numbers depict the numbering according to the von-Baeyer nomenclature for polycyclics. In principle, this nomenclature can also be applied to decahydronaphthalene, which would be called bicyclo[4.4.0]decane. In the case of decahydronaphthalene the blue numbering variant is preferred because decahydronaphthalene consists of two fused cycles with a circumference of 6 atoms each.
<a href="//commons.wikimedia.org/wiki/User:Hbf878" title="User:Hbf878">Hbf878</a>
2018-11-09
<span class="int-own-work" lang="en">Own work</span>