Editing Aromatic compound (section)

=== Monocyclic arenes ===
Of [[annulene]]s larger than benzene, [12]annulene and [14]annulene are weakly aromatic compounds and [18]annulene, [[Cyclooctadecanonaene]], is aromatic, though strain within the structure causes a slight deviation from the precisely planar structure necessary for aromatic categorization.<ref>{{Cite web |date=2013-10-02 |title=What does "aromatic" really mean? |url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Arenes/Properties_of_Arenes/Aromaticity/What_does_aromatic_really_mean |access-date=2023-11-06 |website=Chemistry LibreTexts |language=en}}</ref> Another example of a non-benzylic monocyclic arene is the [[Cyclopropenium ion|cyclopropenyl]] (cyclopropenium cation), which satisfies [[Hückel's rule]] with an n equal to 0.<ref name=":4">{{Cite web |date=2013-10-02 |title=What does "aromatic" really mean? |url=https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Arenes/Properties_of_Arenes/Aromaticity/What_does_aromatic_really_mean |access-date=2023-11-29 |website=Chemistry LibreTexts |language=en}}</ref> Note, only the cationic form of this cyclic propenyl is aromatic, given that neutrality in this compound would violate either the octet rule or [[Hückel's rule]].<ref name=":4" />

Other non-benzylic monocyclic arenes include the aforementioned heteroarenes that can replace carbon atoms with other heteroatoms such as N, O or S.<ref name=":43" /> Common examples of these are the five-membered [[pyrrole]] and six-membered [[pyridine]], both of which have a substituted nitrogen<ref>{{Cite web |date=2020-07-30 |title=4.2: Covalent Bonds |url=https://chem.libretexts.org/Courses/Mount_Aloysius_College/CHEM_100%3A_General_Chemistry_(O'Connor)/04%3A_Covalent_Bonding_and_Simple_Molecular_Compounds/4.02%3A_Covalent_Bonds |access-date=2023-11-06 |website=Chemistry LibreTexts |language=en}}</ref>