Cross-conjugation: Difference between revisions
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'''Cross-conjugation''' is a special type of [[conjugated system|conjugation]] in a [[molecule]], when in a set of three [[ |
'''Cross-conjugation''' is a special type of [[conjugated system|conjugation]] in a [[molecule]], when in a set of three [[pi bond]]s only two pi bonds interact with each other by conjugation, while the third one is excluded from interaction.<ref>{{GoldBookRef|title=cross-conjugation|file = C01404}}</ref><ref>{{cite journal |first1= Nelson F. |last1= Phelan |first2= Milton |last2= Orchin |title= Cross Conjugation |journal= Journal of Chemical Education |year= 1968 |volume= 45 |issue= 10 |pages= 633–637 |doi= 10.1021/ed045p633}}</ref> [[File:Cross Conjugation Triene V.1.svg|thumb|200px]] |
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Whereas a normal conjugated system such as a [[polyene]] typically has alternating single and double bonds along consecutive atoms, a cross-conjugated system has an alkene unit bonded to one of the middle atoms of another conjugated chain through a single bond. In classical terms, one of the double-bonds branches off rather than continuing consecutively: the main chain is conjugated, and part of that same main chain is conjugated with the side group, but all parts are not conjugated together as strongly. Examples of cross-conjugation can be found in molecules such as [[benzophenone]], {{chem name|[[divinylketone]]s}}, [[p-quinone|''p''-quinones]], [[dendralenes]], [[radialene]]s, [[fullerene]], and [[Indigo dye]]. The type of conjugation affects reactivity and [[molecular electronic transition]]s. |
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==References== |
==References== |
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{{Reflist}} |
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== External links == |
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* [http://www.iupac.org/goldbook/C01404.pdf IUPAC definition] |
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[[Category:Chemical bonding]] |
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Latest revision as of 05:38, 24 November 2023
Cross-conjugation is a special type of conjugation in a molecule, when in a set of three pi bonds only two pi bonds interact with each other by conjugation, while the third one is excluded from interaction.[1][2]
Whereas a normal conjugated system such as a polyene typically has alternating single and double bonds along consecutive atoms, a cross-conjugated system has an alkene unit bonded to one of the middle atoms of another conjugated chain through a single bond. In classical terms, one of the double-bonds branches off rather than continuing consecutively: the main chain is conjugated, and part of that same main chain is conjugated with the side group, but all parts are not conjugated together as strongly. Examples of cross-conjugation can be found in molecules such as benzophenone, divinylketones, p-quinones, dendralenes, radialenes, fullerene, and Indigo dye. The type of conjugation affects reactivity and molecular electronic transitions.
References
[edit]- ^ IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "cross-conjugation". doi:10.1351/goldbook.C01404
- ^ Phelan, Nelson F.; Orchin, Milton (1968). "Cross Conjugation". Journal of Chemical Education. 45 (10): 633–637. doi:10.1021/ed045p633.