Thiopyrylium is a

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

with the chemical formula C₅H₅S⁺. It is analogous to the

pyrylium Pyrylium is a cation (positive ion) with formula , consisting of a six-membered ring of five carbon atoms, each with one hydrogen atom, and one positively charged oxygen atom. The bonds in the ring are conjugated as in benzene, giving it an aroma ...

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 Polarizability usually refers to the tendency of matter, when subjected to an electric field, to acquire an electric dipole moment in proportion to that applied field. It is a property of all matter, considering that matter is made up of elementar ...

of the

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

atom. Among the

chalcogen The chalcogens (ore forming) ( ) are the chemical elements in group 16 of the periodic table. This group is also known as the oxygen family. Group 16 consists of the elements oxygen (O), sulfur (S), selenium (Se), tellurium (Te), and the radioact ...

ic 6-membered unsaturated

heterocycle A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different chemical element, elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis ...

s, thiopyrylium is the most

aromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...

, due to sulfur having the similar Pauling electronegativity as carbon and only a slightly higher

covalent radius The covalent radius, ''r''cov, is a measure of the size of an atom that forms part of one covalent bond. It is usually measured either in picometres (pm) or angstroms (Å), with 1 Å = 100 pm. In principle, the sum of the two cova ...

. 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 Thiopyran is a heterocyclic compound with the chemical formula C5H6S. There are two isomers, 2''H''-thiopyran and 4''H''-thiopyran, which differ by the location of double bonds. Thiopyrans are analogous to pyrans in which the oxygen atoms have be ...

by a hydride ion acceptor, such as trityl perchlorate. The thiopyrylium analogue of 2,4,6-trisubstituted pyrylium salts can be synthesized by treatment with

sodium sulfide Sodium sulfide is a chemical compound with the formula Na2 S, or more commonly its hydrate Na2S·9 H2O. Both the anhydrous and the hydrated salts in pure crystalline form are colorless solids, although technical grades of sodium sulfide are gener ...

followed by precipitation with acid. This reaction causes the oxygen atom in the pyrylium cation to be substituted with sulfur.

References

Sulfur heterocycles Cations Six-membered rings {{heterocyclic-stub

See also

References