thiopyrylium

{{Short description|Ion}}

{{Chembox|ImageFile=Thiopyrylium ion structuur.png|ImageSize=100px|ImageAlt=|PIN=Thiopyrylium{{cite book |author=International Union of Pure and Applied Chemistry |date=2014 |title=Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 |publisher=The Royal Society of Chemistry |pages=1097 |doi=10.1039/9781849733069 |isbn=978-0-85404-182-4}}|OtherNames=|Section1={{Chembox Identifiers

|PubChem = 11344401

|ChemSpiderID = 9519339

|SMILES = [s+]1ccccc1

|InChI=1S/C5H5S/c1-2-4-6-5-3-1/h1-5H/q+1

|InChIKey = OKYDCMQQLGECPI-UHFFFAOYSA-N

}}|Section2={{Chembox Properties

|Formula = C₅H₅S⁺

|MolarMass = 97.16 g/mol

|Solubility = Reacts

}}

}}

Thiopyrylium is a cation with the chemical formula C₅H₅S⁺. It is analogous to the pyrylium cation with the oxygen atom replaced by a sulfur atom.

Thiopyrylium salts are less reactive than the analogous pyrylium salts due to the higher polarizability of the sulfur atom.{{cite book | title = Newer Methods of Preparative Organic Chemistry | volume = 3 | author1 = K. Dimroth | author2 = K. H. Wolf | editor = Wilhelm Foerst | publisher = Elsevier | year = 2012 | isbn = 9780323146104 | page = 361}} Among the chalcogenic 6-membered unsaturated heterocycles, thiopyrylium is the most aromatic, due to sulfur having the similar Pauling electronegativity as carbon and only a slightly higher covalent radius.{{cite book | title = Aromaticity in Heterocyclic Compounds | volume = 19 of Topics in Heterocyclic Chemistry |editor1= Tadeusz Marek Krygowski |editor2=Michal Ksawery Cyranski | publisher = Springer | year = 2009 | isbn = 9783540683292 | pages = 219–220}} In water, thiopyrylium reacts to it and forms a mixture of 2-hydroxythiopyran and 4-hydroxythiopyran.{{Citation needed|date=March 2019}}

Thiopyrylium salts can be synthesized by hydrogen abstraction from thiopyran by a hydride ion acceptor, such as trityl perchlorate.{{cite encyclopedia | encyclopedia = Concise Encyclopedia Chemistry | title = Thiopyrans | publisher = Walter de Gruyter | year = 1994 | isbn = 9783110854039 | page = 1101}}

The thiopyrylium analogue of 2,4,6-trisubstituted pyrylium salts can be synthesized by treatment with sodium sulfide followed by precipitation with acid. This reaction causes the oxygen atom in the pyrylium cation to be substituted with sulfur.