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| verifiedrevid = 443022610
| verifiedrevid = 443022610
| Name=Pyrylium
| Name=Pyrylium
| ImageFileL1=Pyrylium.svg
| ImageFileL1 = Pyrylium.svg
| ImageFileR1= Pyrylium-3D-balls.png
| ImageFileR1 = Pyrylium-3D-balls.png
| IUPACName= Pyrylium
| IUPACName = Pyrylium
| OtherNames=
| OtherNames = Pyranium
|Section1={{Chembox Identifiers
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|correct|??}}
| CASNo_Ref = {{cascite|correct|??}}
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| PubChem=9548819
| PubChem = 9548819
| ChEBI_Ref = {{ebicite|changed|EBI}}
| ChEBI_Ref = {{ebicite|changed|EBI}}
| ChEBI = 36120
| ChEBI = 36120
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| StdInChIKey = WVIICGIFSIBFOG-UHFFFAOYSA-N
| StdInChIKey = WVIICGIFSIBFOG-UHFFFAOYSA-N
}}
}}
|Section2={{Chembox Properties
|Section2={{Chembox Properties
| Formula=C<sub>5</sub>H<sub>5</sub>O<sup>+</sup>
| Formula=C<sub>5</sub>H<sub>5</sub>O<sup>+</sup>
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The '''pyrylium''' [[cation]] is a six-membered, unsaturated, mono-[[cyclic compound]]. Consisting of five [[carbon]] atoms and one positively charged [[oxygen]] atom, it is a [[heterocyclic compound]], resembling [[benzene]] with one substitution in the ring. Like [[benzene]], it is [[aromaticity|aromatic]], and a [[conjugated system]]. Having three bonds on its positively charged [[oxygen]] atom, pyrylium is an [[oxonium ion]].


[[Derivative (chemistry)|Derivatives]] of the pyrylium cation are also called '''pyrylium'''.
⚫
A '''pyrylium salt''' is a [[salt]] containing a pyrylium cation or a [[Derivative (chemistry)|derivative]] of it.<ref>{{cite book | title = Heterocyclic Chemistry | author = Gilchrist, T. L. | isbn = 0-582-27843-0 }}</ref><ref>{{cite journal | author = Balaban, A. T. ; Schroth, W.; Fischer, G. | title = Pyrylium Salts. I. Synthesis | journal = Advances in Heterocyclic Chemistry | editor = Katritzky, A. R.; Boulton, A. J. | publisher = Academic Press | location = New York | year = 1969 | volume = 10 | pages = 241–326 | doi = 10.1016/S0065-2725(08)60499-7 }}</ref><ref>{{cite book | author = Balaban, A. T.; Dinculescu, A.; Dorofeenko, G. N.; Fischer, G. W.; Koblik, A. V.; Mezheritskii, V. V.; Schroth, W. | title = Pyrylium Salts. Syntheses, Reactions and Physical Properties | series = Advances in Heterocyclic Chemistry: Supplement | volume = 2 | editor = Katritzky, A. R. | publisher = Academic Press | location = New York | year = 1982 | isbn = 978-0-12-020652-0 }}</ref><ref>{{cite book | author = Balaban, A. T. | chapter = The Pyrylium Cation as a Synthon in Organic Chemistry | title = New Trends in Heterocyclic Chemistry | editor = Mitra, R. B.; Ayyangar, N. R.; Gogte, V. N.; Acheson, R. M.; Cromwell, N. | publisher = Elsevier | location = Amsterdam | year = 1979 | pages = 79–111 | isbn = 978-0-444-41737-4 | series = Studies in Organic Chemistry | volume = 3 }}</ref><ref> {{cite book | author = Balaban, A. T. | chapter = Pyrylium Salts as Useful Synthons | title = Organic Synthesis: Modern Trends | editor = Chizov, O. | publisher = Blackwell | location = Oxford | year = 1987 | pages = 263–274 | isbn = 0-632-02014-8 }}</ref><ref>{{cite book | author = Balaban, T. S.; Balaban, A. T. | chapter = Pyrylium Salts | series = Science of Synthesis; Houben-Weyl Methods of Molecular Transformations | publisher = Georg Thieme Verlag | location = Stuttgart | year = 2003 | volume = 14 | title = Hetarenes and Related Ring Systems, Six-membered Hetarenes with one Chalcogen | pages = 11–200 | isbn = 978-3-13-118641-6 }}</ref>
The pyrylium cation is a [[conjugated system|conjugated]] 6-membered [[carbon]] ring system with one carbon atom replaced by a positively charged [[oxygen]] atom. It is, like [[benzene]], an [[Aromaticity|aromatic]] compound.<br /> A '''pyrylium''' may be any derivative of the pyrylium cation.


⚫
A pyrylium salt is a [[salt]] containing a pyrylium cation or a derivative cation.<ref>{{cite book |title= Heterocyclic Chemistry |author= Gilchrist, T. L. |isbn= 0-582-27843-0}}</ref><ref>{{cite journal |author= Balaban, A. T.; Schroth, W.; Fischer, G. |title= Pyrylium Salts. I. Synthesis |journal= Advances in Heterocyclic Chemistry |editor= Katritzky, A. R.; Boulton, A. J. |publisher= Academic Press |location= New York |year= 1969 |volume= 10 |pages= 241–326 |doi= 10.1016/S0065-2725(08)60499-7}}</ref><ref>{{cite book |author= Balaban, A. T.; Dinculescu, A.; Dorofeenko, G. N.; Fischer, G. W.; Koblik, A. V.; Mezheritskii, V. V.; Schroth, W. |title= Pyrylium Salts. Syntheses, Reactions and Physical Properties |series= Advances in Heterocyclic Chemistry: Supplement |volume= 2 |editor= Katritzky, A. R. |publisher= Academic Press |location= New York |year= 1982 |isbn= 978-0-12-020652-0}}</ref><ref>{{cite book |author= Balaban, A. T. |chapter= The Pyrylium Cation as a Synthon in Organic Chemistry |title= New Trends in Heterocyclic Chemistry |editor= Mitra, R. B.; Ayyangar, N. R.; Gogte, V. N.; Acheson, R. M.; Cromwell, N. |publisher= Elsevier |location= Amsterdam |year= 1979 |pages= 79–111 |isbn= 978-0-444-41737-4 |series= Studies in Organic Chemistry |volume= 3}}</ref><ref> {{cite book |author= Balaban, A. T. |chapter= Pyrylium Salts as Useful Synthons |title= Organic Synthesis: Modern Trends |editor= Chizov, O. |publisher= Blackwell |location= Oxford |year= 1987 |pages= 263–274 |isbn= 0-632-02014-8}}</ref><ref>{{cite book |author= Balaban, T. S.; Balaban, A. T. |chapter= Pyrylium Salts |series= Science of Synthesis; Houben-Weyl Methods of Molecular Transformations |publisher= Georg Thieme Verlag |location= Stuttgart |year= 2003 |volume= 14 |title= Hetarenes and Related Ring Systems, Six-membered Hetarenes with one Chalcogen |pages= 11–200 |isbn= 978-3-13-118641-6}}</ref>
⚫
==Chemical properties==
⚫
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 [[nucleophile]]s 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.


⚫
==Chemical properties==
⚫
Being aromatic, pyrylium salts are easily formed from simple starting materials, and their reactivity toward nucleophiles makes them useful materials for obtaining other compounds with stronger aromatic character. Thus, pyrylium salts afford pyridines with ammonia,<ref>{{OrgSynth | author = Anderson, A. G.; Stang, P. J. | title = 2,6-Di-''tert''-Butyl-4-Methylpyridine | collvol = 7 | collvolpages = 144 | year = 1981 | volume = 60 | pages = 34 | prep = cv7p0144 | url = http://www.orgsyn.org/orgsyn/pdfs/CV7P0144.pdf }}</ref> pyridinium salts with primary amines, pyridine-N-oxides with hydroxylamine, phosphabenzenes with phosphine derivatives, [[thiopyrylium]] salts with hydrogen sulfide, and benzene derivatives with [[acetonitrile]] or [[nitromethane]].
⚫
Like other [[oxonium ion]]s, pyrylium is unstable in neutral water. However, pyrylium is much less reactive than ordinary oxonium ions because of aromatic stabilization. Pyrylium cations react with [[nucleophile]]s in the 2,4, and 6 positions, which can induce ring-opening reactions. The high electronegativity of the oxygen results in the strongest single perturbation by one [[heteroatom]] in a six-membered ring.


==Synthesis==
==Synthesis==
Being aromatic, pyrylium salts are easily produced from simple starting materials.
⚫
Pyrylium salts with aromatic substituents such 2,4,6-triphenylpyrylium tetrafluoroborate can be obtained from two moles of [[acetophenone]] and one mole of [[benzaldehyde]] in the presence of [[tetrafluoroboric acid]] and an oxidizing agent ('''Dilthey synthesis'''). For pyrylium salts with alkyl substituents such as 2,4,6-trimethylpyrylium salts, the best method uses the '''[[Alexandru Balaban|Balaban]]-[[Costin Nenițescu|Nenitzescu]]-Praill synthesis''' from tertiary butanol and [[acetic anhydride]] in the presence of tetrafluoroboric, perchloric, or trifluoromethanesulfonic acids.<ref>{{OrgSynth | author = Balaban, A. T.; Boulton, A. J. | collvol = 5 | collvolpages = 1112–1113 | year = 1973 | title = 2,4,6-Trimethyl-Pyrylium Tetrafluoroborate | prep = cv5p1112 | url = http://www.orgsyn.org/orgsyn/pdfs/CV5P1112.pdf }}</ref><ref>{{OrgSynth | author = Balaban, A. T.; Boulton, A. J. | collvol = 5 | collvolpages = 1114–1116 | year = 1973 | title = 2,4,6-Trimethyl-Pyrylium Trifluoromethanesulfonate | prep = cv51114 | url = http://www.orgsyn.org/orgsyn/pdfs/CV5P1114.pdf }}</ref> 2,4,6-Triphenylpyrylium salts are converted by bases into stable a 1,5-enedione (pseudobase) but 2,4,6-trimethylpyrylium salts on treatment with hot alkali hydroxides afford an unstable pseudobase that undergoes an intramolecular condensation yielding 3,5-dimethylphenol. In warm deuterium oxide, 2,4,6-trimethylpyrylium salts undergo isotopic exchange of 4-methyl hydrogens faster than for the 2- and 6-methyl groups, allowing the synthesis of regioselectively deuterated compounds.

⚫
Pyrylium salts with aromatic substituents, such 2,4,6-triphenylpyrylium tetrafluoroborate, can be obtained from two moles of [[acetophenone]] and one mole of [[benzaldehyde]] in the presence of [[tetrafluoroboric acid]] and an oxidizing agent (Dilthey synthesis). For pyrylium salts with alkyl substituents, such as 2,4,6-trimethylpyrylium salts, the best method uses the [[Alexandru Balaban|Balaban]]-[[Costin Nenițescu|Nenitzescu]]-Praill synthesis from [[tert-Butyl alcohol|tertiary butanol]] and [[acetic anhydride]] in the presence of tetrafluoroboric, perchloric, or trifluoromethanesulfonic acids.<ref>{{OrgSynth |author= Balaban, A. T.; Boulton, A. J. |collvol= 5 |collvolpages= 1112–1113 |year= 1973 |title= 2,4,6-Trimethyl-Pyrylium Tetrafluoroborate |prep= cv5p1112 |url= http://www.orgsyn.org/orgsyn/pdfs/CV5P1112.pdf}}</ref><ref>{{OrgSynth |author= Balaban, A. T.; Boulton, A. J. |collvol= 5 |collvolpages= 1114–1116 |year= 1973 |title= 2,4,6-Trimethyl-Pyrylium Trifluoromethanesulfonate |prep= cv51114 |url= http://www.orgsyn.org/orgsyn/pdfs/CV5P1114.pdf}}</ref> 2,4,6-Triphenylpyrylium salts are converted by bases into stable a 1,5-enedione (pseudobase), but 2,4,6-trimethylpyrylium salts on treatment with hot alkali hydroxides afford an unstable pseudobase that undergoes an intramolecular condensation yielding 3,5-[[xylenol|dimethylphenol]]. In warm deuterium oxide, 2,4,6-trimethylpyrylium salts undergo isotopic exchange of 4-methyl hydrogens faster than for the 2- and 6-methyl groups, allowing the synthesis of regioselectively deuterated compounds.

==Derivatives==
⚫
The reactivity of pyrylium salts toward nucleophiles makes them useful materials for producing other compounds with stronger aromatic character. Pyrylium salts afford [[pyridine]]s with [[ammonia]],<ref>{{OrgSynth |author= Anderson, A. G.; Stang, P. J. |title= 2,6-Di-''tert''-Butyl-4-Methylpyridine |collvol= 7 |collvolpages= 144 |year= 1981 |volume= 60 |pages= 34 |prep= cv7p0144 |url= http://www.orgsyn.org/orgsyn/pdfs/CV7P0144.pdf}}</ref> [[pyridinium]] salts with primary amines, [[pyridine-N-oxide]]s with [[hydroxylamine]], [[phosphabenzene]]s with [[phosphine]] derivatives, [[thiopyrylium]] salts with [[hydrogen sulfide]], and benzene derivatives with [[acetonitrile]] or [[nitromethane]].


==Pyrones==
==Pyrones==
[[File:Pyrones.png|210 px|right|pyrones]]
[[File:Pyrones.png|210 px|right|pyrones]]
A pyrylium cation with a [[hydroxyl]] anion [[substituent]] in the 2-position is not the [[zwitterion]]ic aromatic compound ('''1''') but a neutral [[Saturation (chemistry)|unsaturated]] [[lactone]] or an [[2-pyrone|α-pyrone]] or pyran-2-one ('''2'''). Important representatives of this class are the [[coumarin]]s. Likewise a 4-hydroxyl pyrylium compound is a φ-pyrone or pyran-4-one ('''4''') to which group belongs a compound such like [[maltol]].
A pyrylium cation with a [[hydroxyl]] anion [[substituent]] in the 2-position is not the [[zwitterion]]ic aromatic compound ('''1'''), but a neutral [[saturation (chemistry)|unsaturated]] [[lactone]] or an [[2-Pyrone|2-pyrone]] or pyran-2-one ('''2'''). Important representatives of this class are the [[coumarin]]s. Likewise a 4-hydroxyl pyrylium compound is a φ-pyrone or pyran-4-one ('''4'''), to which group belong compounds such as [[maltol]].


===Chemical properties===
===Chemical properties===
⚫
2-Pyrones are known to react with [[alkyne]]s in a [[Diels-Alder reaction]] to form [[arene compound]]s with expulsion of [[carbon dioxide]], for example:<ref> {{cite journal | author = Delaney, P. M.; Moore, J. E.; Harrity, J. P. A. | title = An Alkynylboronic Ester Cycloaddition Route to Functionalised Aromatic Boronic Esters | journal = [[Chemical Communications]] | year = 2006 | volume = 2006 | issue = 31 | pages = 3323–3325 | doi = 10.1039/b607322k }}</ref>

[[File:Pyronecycloaddition.png|400px|center|Pyrone cycloaddition]]
[[File:Pyronecycloaddition.png|400px|center|Pyrone cycloaddition]]
⚫
2-Pyrones are known to react with [[alkyne]]s in a [[Diels–Alder reaction]] to form [[arene]] compounds with expulsion of [[carbon dioxide]], for example:<ref> {{cite journal |author= Delaney, P. M.; Moore, J. E.; Harrity, J. P. A. |title= An Alkynylboronic Ester Cycloaddition Route to Functionalised Aromatic Boronic Esters |journal= [[Chemical Communications]] |year= 2006 |volume= 2006 |issue= 31 |pages= 3323–3325 |doi= 10.1039/b607322k}}</ref>


==Larger pyriliums==
==Chromenylium ion==
===Chromenylium ion===
⚫
[[File:Benzopyryliumchlorid.svg|thumb|140px|Chromenylium (benzopyrylium) salt with chloride as the [[counterion]]]]
The benzo-fused pyrylium ion is also called benzopyrilium or according to [[IUPAC]] chromenylium ion (Formula: C<sub>9</sub>H<sub>7</sub>O, molar mass: 131.15 g/mol, exact mass: 131.04968983). This is the charged version of [[benzopyran|1-benzopyran]] or [[chromene]] (IUPAC).
The benzo-fused pyrylium ion is called benzopyrilium ([[IUPAC]]: chromenylium ion) (Formula: {{Chem|C|9|H|7|O|+}}, molar mass: 131.15 g/mol, exact mass: 131.04968983). It can be seen as a charged derivative of 2H-1-[[benzopyran]] (IUPAC: 2H-chromene), {{Chem|C|9|H|8|O}}.
{{clear}}


==Flavylium ion==
===Flavylium ion===
⚫
In biology, the 2-phenylchromenylium ion is referred to as flavylium. A class of flavylium-derived compounds are [[anthocyanidin]]s and [[anthocyanin]]s, pigments that are responsible for the colors of many flowers.


⚫
===Naphthoxanthenium cation===
⚫
In biology, the 2-phenylchromenylium ion is referred to as flavylium. A class of flavylium derived compounds are [[anthocyanidin]]s and [[anthocyanins]], i.e., pigments that are responsible for the colors of many flowers.[[File:Flavylium cation.svg|thumb|200px|Flavylium cation]]
⚫
Higher fused derivatives of pyrilium also exist. One good example is the naphthoxanthenium derivative. This dye is highly stable, aromatic, and planar. It absorbs in the UV and blue region and presents exceptional photophysical properties. It can be synthesized by chemical or photochemical reactions.<ref>{{cite journal |author= Bucher, G.; Bresolí-Obach, R.; Brosa, C.; Flors, C.; Luis, J. L.; Grillo, T. A.; Nonell, S. |title= β-Phenyl quenching of 9-phenylphenalenones: a novel photocyclisation reaction with biological implications |journal= [[Physical Chemistry Chemical Physics]] |year= 2014 |volume= 16 |pages= 18813-18820 |doi= 10.1039/C4CP02783C}}</ref>
{{clear}}
<gallery widths=200px>

⚫
File:Benzopyryliumchlorid.svg|Benzopyrylium chloride (chromenylium chloride), a salt with [[chloride]] as the [[counterion]]
⚫
==Naphthoxanthenium cation==
File:Flavylium cation.svg|Flavylium cation

⚫
File:Naphthoxanthenium.tif|Naphthoxanthenium cation
⚫
Higher fused derivatives of pyrilium also exist. One good example is the naphthoxanthenium derivative. This dye is highly stable, aromatic and planar. It absorbs in the UV and blue region and presents exceptional photophysical properties. It can be synthesized by chemical or photochemical reactions.<ref>{{cite journal | author = Bucher, G.; Bresolí-Obach, R.; Brosa, C.; Flors, C.; Luis, J. L.; Grillo, T. A.; Nonell, S. | title = β-Phenyl quenching of 9-phenylphenalenones: a novel photocyclisation reaction with biological implications | journal = [[Physical Chemistry Chemical Physics]] | year = 2014 | volume = 16 | pages = 18813-18820 | doi = 10.1039/C4CP02783C }}</ref>
</gallery>

⚫
[[File:Naphthoxanthenium.tif|thumb|Naphthoxanthenium cation]]

⚫
== See also ==
⚫
* 6-membered aromatic rings with one carbon replaced by another group: [[borabenzene]], [[benzene]], [[silabenzene]], [[germabenzene]], [[stannabenzene]], [[pyridine]], [[phosphorine]], [[arsabenzene]], '''pyrylium salt'''
⚫
* [[Pyran]]s are pyrones lacking the ketone group.


⚫
==See also==
⚫
*6-membered aromatic rings ([[benzene]]) with one carbon replaced by a different atom: [[borabenzene]], [[pyridine]], '''pyrylium''', [[silabenzene]], [[phosphorine]], [[arsabenzene]], [[germabenzene]], [[stannabenzene]]
⚫
*[[Pyran]], {{Chem|C|5|H|6|O}} (pyrones lacking the ketone group)
{{wiktionary|pyrylium}}
{{wiktionary|pyrylium}}


== References ==
==References==
{{reflist}}
{{reflist}}






{{DEFAULTSORT:Pyrylium Salt}}
{{DEFAULTSORT:Pyrylium Salt}}

Revision as of 06:41, 20 January 2016

Pyrylium
Names
IUPAC name
Pyrylium
Other names
Pyranium
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
  • InChI=1S/C5H5O/c1-2-4-6-5-3-1/h1-5H/q+1 ☒N
    Key: WVIICGIFSIBFOG-UHFFFAOYSA-N ☒N
  • InChI=1/C5H5O/c1-2-4-6-5-3-1/h1-5H/q+1
    Key: WVIICGIFSIBFOG-UHFFFAOYAF
  • C1=CC=[O+]C=C1
Properties
C5H5O+
Molar mass 81.09 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
☒N verify (what is checkY☒N ?)

The pyrylium cation is a six-membered, unsaturated, mono-cyclic compound. Consisting of five carbon atoms and one positively charged oxygen atom, it is a heterocyclic compound, resembling benzene with one substitution in the ring. Like benzene, it is aromatic, and a conjugated system. Having three bonds on its positively charged oxygen atom, pyrylium is an oxonium ion.

Derivatives of the pyrylium cation are also called pyrylium.

A pyrylium salt is a salt containing a pyrylium cation or a derivative cation.[1][2][3][4][5][6]

Chemical properties

Like other oxonium ions, pyrylium is unstable in neutral water. However, pyrylium is much less reactive than ordinary oxonium ions because of aromatic stabilization. Pyrylium cations react with nucleophiles in the 2,4, and 6 positions, which can induce ring-opening reactions. The high electronegativity of the oxygen results in the strongest single perturbation by one heteroatom in a six-membered ring.

Synthesis

Being aromatic, pyrylium salts are easily produced from simple starting materials.

Pyrylium salts with aromatic substituents, such 2,4,6-triphenylpyrylium tetrafluoroborate, can be obtained from two moles of acetophenone and one mole of benzaldehyde in the presence of tetrafluoroboric acid and an oxidizing agent (Dilthey synthesis). For pyrylium salts with alkyl substituents, such as 2,4,6-trimethylpyrylium salts, the best method uses the Balaban-Nenitzescu-Praill synthesis from tertiary butanol and acetic anhydride in the presence of tetrafluoroboric, perchloric, or trifluoromethanesulfonic acids.[7][8] 2,4,6-Triphenylpyrylium salts are converted by bases into stable a 1,5-enedione (pseudobase), but 2,4,6-trimethylpyrylium salts on treatment with hot alkali hydroxides afford an unstable pseudobase that undergoes an intramolecular condensation yielding 3,5-dimethylphenol. In warm deuterium oxide, 2,4,6-trimethylpyrylium salts undergo isotopic exchange of 4-methyl hydrogens faster than for the 2- and 6-methyl groups, allowing the synthesis of regioselectively deuterated compounds.

Derivatives

The reactivity of pyrylium salts toward nucleophiles makes them useful materials for producing other compounds with stronger aromatic character. Pyrylium salts afford pyridines with ammonia,[9] pyridinium salts with primary amines, pyridine-N-oxides with hydroxylamine, phosphabenzenes with phosphine derivatives, thiopyrylium salts with hydrogen sulfide, and benzene derivatives with acetonitrile or nitromethane.

Pyrones

pyrones
pyrones

A pyrylium cation with a hydroxyl anion substituent in the 2-position is not the zwitterionic aromatic compound (1), but a neutral unsaturated lactone or an 2-pyrone or pyran-2-one (2). Important representatives of this class are the coumarins. Likewise a 4-hydroxyl pyrylium compound is a φ-pyrone or pyran-4-one (4), to which group belong compounds such as maltol.

Chemical properties

Pyrone cycloaddition
Pyrone cycloaddition

2-Pyrones are known to react with alkynes in a Diels–Alder reaction to form arene compounds with expulsion of carbon dioxide, for example:[10]

Larger pyriliums

Chromenylium ion

The benzo-fused pyrylium ion is called benzopyrilium (IUPAC: chromenylium ion) (Formula: C
9H
7O+
, molar mass: 131.15 g/mol, exact mass: 131.04968983). It can be seen as a charged derivative of 2H-1-benzopyran (IUPAC: 2H-chromene), C
9H
8O.

Flavylium ion

In biology, the 2-phenylchromenylium ion is referred to as flavylium. A class of flavylium-derived compounds are anthocyanidins and anthocyanins, pigments that are responsible for the colors of many flowers.

Naphthoxanthenium cation

Higher fused derivatives of pyrilium also exist. One good example is the naphthoxanthenium derivative. This dye is highly stable, aromatic, and planar. It absorbs in the UV and blue region and presents exceptional photophysical properties. It can be synthesized by chemical or photochemical reactions.[11]

  • Benzopyrylium chloride (chromenylium chloride), a salt with chloride as the counterion
    Benzopyrylium chloride (chromenylium chloride), a salt with chloride as the counterion
  • Flavylium cation
    Flavylium cation
  • Naphthoxanthenium cation
    Naphthoxanthenium cation

See also

Look up pyrylium in Wiktionary, the free dictionary.

References

  1. ^ Gilchrist, T. L. Heterocyclic Chemistry. ISBN 0-582-27843-0.
  2. ^ Balaban, A. T.; Schroth, W.; Fischer, G. (1969). Katritzky, A. R.; Boulton, A. J. (ed.). "Pyrylium Salts. I. Synthesis". Advances in Heterocyclic Chemistry. 10. New York: Academic Press: 241–326. doi:10.1016/S0065-2725(08)60499-7.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  3. ^ Balaban, A. T.; Dinculescu, A.; Dorofeenko, G. N.; Fischer, G. W.; Koblik, A. V.; Mezheritskii, V. V.; Schroth, W. (1982). Katritzky, A. R. (ed.). Pyrylium Salts. Syntheses, Reactions and Physical Properties. Advances in Heterocyclic Chemistry: Supplement. Vol. 2. New York: Academic Press. ISBN 978-0-12-020652-0.{{cite book}}: CS1 maint: multiple names: authors list (link)
  4. ^ Balaban, A. T. (1979). "The Pyrylium Cation as a Synthon in Organic Chemistry". In Mitra, R. B.; Ayyangar, N. R.; Gogte, V. N.; Acheson, R. M.; Cromwell, N. (ed.). New Trends in Heterocyclic Chemistry. Studies in Organic Chemistry. Vol. 3. Amsterdam: Elsevier. pp. 79–111. ISBN 978-0-444-41737-4.{{cite book}}: CS1 maint: multiple names: editors list (link)
  5. ^ Balaban, A. T. (1987). "Pyrylium Salts as Useful Synthons". In Chizov, O. (ed.). Organic Synthesis: Modern Trends. Oxford: Blackwell. pp. 263–274. ISBN 0-632-02014-8.
  6. ^ Balaban, T. S.; Balaban, A. T. (2003). "Pyrylium Salts". Hetarenes and Related Ring Systems, Six-membered Hetarenes with one Chalcogen. Science of Synthesis; Houben-Weyl Methods of Molecular Transformations. Vol. 14. Stuttgart: Georg Thieme Verlag. pp. 11–200. ISBN 978-3-13-118641-6.{{cite book}}: CS1 maint: multiple names: authors list (link)
  7. ^ Balaban, A. T.; Boulton, A. J. (1973). "2,4,6-Trimethyl-Pyrylium Tetrafluoroborate" (PDF). Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 5, pp. 1112–1113.
  8. ^ Balaban, A. T.; Boulton, A. J. (1973). "2,4,6-Trimethyl-Pyrylium Trifluoromethanesulfonate" (PDF). Organic Syntheses{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 5, pp. 1114–1116.
  9. ^ Anderson, A. G.; Stang, P. J. (1981). "2,6-Di-tert-Butyl-4-Methylpyridine" (PDF). Organic Syntheses. 60: 34{{cite journal}}: CS1 maint: multiple names: authors list (link); Collected Volumes, vol. 7, p. 144.
  10. ^ Delaney, P. M.; Moore, J. E.; Harrity, J. P. A. (2006). "An Alkynylboronic Ester Cycloaddition Route to Functionalised Aromatic Boronic Esters". Chemical Communications. 2006 (31): 3323–3325. doi:10.1039/b607322k.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  11. ^ Bucher, G.; Bresolí-Obach, R.; Brosa, C.; Flors, C.; Luis, J. L.; Grillo, T. A.; Nonell, S. (2014). "β-Phenyl quenching of 9-phenylphenalenones: a novel photocyclisation reaction with biological implications". Physical Chemistry Chemical Physics. 16: 18813–18820. doi:10.1039/C4CP02783C.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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