Pyrylium Salt

Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A pyrylium salt is a salt containing a pyrylium cation or a derivative of it. The pyrylium cation is a conjugated 6-membered carbon ring system with one carbon atom replaced by a positively charged oxygen atom. It is, like benzene, an aromatic compound. A pyrylium may be any derivative of the pyrylium cation. The carbon to oxygen double bond is also an oxonium ion which due to aromatic stabilization is much less reactive than ordinary oxonium ions. However, the parent compound pyrylium is unstable in neutral water like oxonium salts. Pyrylium cations react with nucleophiles in the 2,4 and 6 positions and may result in ring-opening reactions. The high electronegativity of the oxygen results in the strongest single perturbation of one heteroatom in a six-membered ring.