:Talk:Arene substitution pattern

I followed this link from "para-" on the disambiguation page, expecting to find information on the prefix meanin "Beside; near; alongside". Why is it linked to a rather involved page on chemistry? —Preceding unsigned comment added by 88.105.81.182 (talk) 19:19, 20 November 2007 (UTC)

• It should link to para V8rik (talk) 20:06, 20 November 2007 (UTC)

• I have now modified the dab page to try to send both linguists and chemists (like me) to the right place. For the first (linguistic) meaning, I didn't find an appropriate article on the para affix so I removed the link on para and inserted one for affix. For the chemical meaning further down, I inserted the words "in chemistry" to warn away users interested in other meanings. Dirac66 (talk) 22:46, 20 November 2007 (UTC)

Image:Ipso Substitution V.3.svg|ipso- substitution.

Image:Meso Substitution V.1.svg|meso- substitution.

Image:Peri Substitution V.1.svg|peri- substitution.

Having completely failed to mentally grasp those images, I roamed the Intertubes until I found this:

• [https://www.thoughtco.com/ipso-meso-and-peri-substitutions-608695 Ipso, Meso, and Peri Substitutions in Organic Chemistry] — August 2018

Particularly the main image at the top of that page helped the penny to finally drop: [https://www.thoughtco.com/thmb/TicpH8jr1kh7mrtPw1rzG-yhGeI=/768x0/filters:no_upscale():max_bytes(150000):strip_icc()/ipso-meso-peri-structures-58b5bbd33df78cdcd8b65db1.png image]

Drawn differently, I finally grasped that the blue arrow thing implies a second instance of R (designated R').

But then there's more:

Peri-substitution occurs in naphthalenes for substituents at the 1 and 8 positions.

I can find no reference that documents carbon position 8. When I count cyclodecane myself, by the obvious approach of crawling around the outside like an ant, the positions illustrated come out as 1 and 9 (with final position 10 in between).

The following rather imposing document does not illustrate how to enumerate the carbons in cyclodecane.

• [https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Alkanes/Nomenclature_of_Alkanes/Nomenclature_of_Cycloalkanes Nomenclature of Cycloalkanes] — updated 5 June 2019

Nor was I able to find such an enumeration in any obvious Wikipedia page concerning cyclic carbon chemistry or formal naming systems.

More work required. — MaxEnt 16:00, 23 June 2020 (UTC)