Thiopyrylium

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
Identifiers
3D model (JSmol)
ChemSpider
Properties
C5H5S+
Molar mass 97.16 g/mol
Reacts
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Thiopyrylium salts are less reactive than the analogous pyrylium salts due to the higher polarizability of the sulfur atom.[1][2] 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.[1] In water, thiopyrylium reacts to it and forms a mixture of 2-hydroxythiopyran and 4-hydroxythiopyran.

Thiopyrylium salts can be synthesized by hydrogen abstraction from thiopyran by a hydride ion acceptor, such as trityl perchlorate.[3]

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.[2]

See also

References
  1. Tadeusz Marek Krygowski; Michal Ksawery Cyranski, eds. (2009). Aromaticity in Heterocyclic Compounds. Volume 19 of Topics in Heterocyclic Chemistry. Springer. pp. 219–220. ISBN 9783540683292.
  2. K. Dimroth; K. H. Wolf (2012). Wilhelm Foerst (ed.). Newer Methods of Preparative Organic Chemistry. 3. Elsevier. p. 361. ISBN 9780323146104.
  3. "Thiopyrans". Concise Encyclopedia Chemistry. Walter de Gruyter. 1994. p. 1101. ISBN 9783110854039.


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