For example, oxepane is a 7-atom ring. Can there be 8-atom ring or 9-atom ring … or million-atom ring to infinity?

  • 3
    $\begingroup$ Million atom sized rings do not make a lot of sense to me. $\endgroup$ Commented Mar 14, 2014 at 7:36
  • $\begingroup$ Yes, as @Klaus-DieterWarzecha has stated, there are certain rules that govern how organic compounds are formed, such that a million atom sized ring is not plausible. $\endgroup$
    – H. Khan
    Commented May 20, 2018 at 19:49

3 Answers 3


To my knowledge, the Hantzsch-Widman nomenclature defines stems for ring sizes up to 10 (ecine for unsaturated, ecane for saturated heterocycles).

Oxepane is not the general stem for a seven-membered heterocyclic ring, but the suffix for one containing an oxygen atom.


According to the current version of Nomenclature of Organic Chemistry – IUPAC Recommendations and Preferred Names 2013 (Blue Book), heteromonocyclic compounds with up to and including ten ring members are named by the extended Hantzsch–Widman system; for example

  • oxirane ($\ce{C2H4O}$)
  • oxetane ($\ce{C3H6O}$)
  • oxolane ($\ce{C4H8O}$)
  • oxane ($\ce{C5H10O}$)
  • oxepane ($\ce{C6H12O}$)
  • oxocane ($\ce{C7H14O}$)
  • oxonane ($\ce{C8H16O}$)
  • oxecane ($\ce{C9H18O}$)

For monocyclic rings with eleven and more ring members, skeletal replacement (‘a’) nomenclature is used; for example

  • oxacycloundecane ($\ce{C10H20O}$)
  • oxacyclododecane ($\ce{C11H22O}$)
  • oxacyclotridecane ($\ce{C12H24O}$)
  • oxacyclotetradecane ($\ce{C13H26O}$)
  • oxacyclopentadecane ($\ce{C14H28O}$)
  • etc.

Theoretically speaking, I don't see why not. In theory, it should be possible for a million-atom ring to exist. But, of course, in practice, and regarding reality as we currently know it, it isn't something that has been observed or produced, so far.

For example, here is a ring of 36 carbon atoms called cyclohexatriacontane:

enter image description here

And with IUPAC nomenclature, you can name such compounds or rings with a very high number of carbon atoms.

Regarding a ring of carbon infinity, that definitely does not exist in our universe. It sounds closer to religion, or at least multi-verse theory, than chemistry to me, for example.


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