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- Q5198699 subject Q8254863.
- Q5198699 subject Q8255981.
- Q5198699 abstract "Cyclododecahexaene or [12]annulene (C12H12) is a member of a series of annulenes with some interest in organic chemistry with regard to the study of aromaticity These compounds are in general unstable due to their antiaromaticity and built-up of steric strain. On the other hand the di-anion with 14 electrons is a Hückel aromat and more stable. According to in silico experiments the tri-trans isomer is expected to be the most stable, followed by the 1,7-ditrans and the all cis-isomers (+1 kcal/mol) and by the 1,5-ditrans isomer (+5 kcal/mol). The first [12]annulene with sym-tri-trans configuration was synthesized in 1970 from a tricyclic precursor by photolysis at low temperatures. On heating the compound rearranges to a bicyclic [6,4,0] isomer. Reducing the compound at low temperatures allowed analysis of the dianion by proton NMR with the inner protons resonating at - 4.5 ppm relative to TMS, evidence of an aromatic diamagnetic ring current.In one study the 1,7-ditrans isomer is generated at low temperatures in THF by dehydrohalogenation of a hexabromocyclododecane with potassium tert-butoxide. Reduction of this compound at low temperature with caesium metal leads first to the radical anion and then to the dianion. The chemical shift for the internal protons in this compound is with +0.2 ppm much more modest than in the tri-trans isomer.Heating the radical ion solution to room temperature leads to loss of one equivalent of hydrogen and formation of the heptalene radical anion.".
- Q5198699 thumbnail 12-annulene.svg?width=300.
- Q5198699 wikiPageWikiLink Q1108.
- Q5198699 wikiPageWikiLink Q111092.
- Q5198699 wikiPageWikiLink Q11351.
- Q5198699 wikiPageWikiLink Q16814.
- Q5198699 wikiPageWikiLink Q192572.
- Q5198699 wikiPageWikiLink Q1979695.
- Q5198699 wikiPageWikiLink Q1993452.
- Q5198699 wikiPageWikiLink Q2027399.
- Q5198699 wikiPageWikiLink Q210390.
- Q5198699 wikiPageWikiLink Q2161141.
- Q5198699 wikiPageWikiLink Q225972.
- Q5198699 wikiPageWikiLink Q278332.
- Q5198699 wikiPageWikiLink Q283611.
- Q5198699 wikiPageWikiLink Q285903.
- Q5198699 wikiPageWikiLink Q3045102.
- Q5198699 wikiPageWikiLink Q36496.
- Q5198699 wikiPageWikiLink Q425083.
- Q5198699 wikiPageWikiLink Q4795520.
- Q5198699 wikiPageWikiLink Q534307.
- Q5198699 wikiPageWikiLink Q574842.
- Q5198699 wikiPageWikiLink Q7913889.
- Q5198699 wikiPageWikiLink Q8254863.
- Q5198699 wikiPageWikiLink Q8255981.
- Q5198699 wikiPageWikiLink Q899127.
- Q5198699 comment "Cyclododecahexaene or [12]annulene (C12H12) is a member of a series of annulenes with some interest in organic chemistry with regard to the study of aromaticity These compounds are in general unstable due to their antiaromaticity and built-up of steric strain. On the other hand the di-anion with 14 electrons is a Hückel aromat and more stable.".
- Q5198699 label "Cyclododecahexaene".
- Q5198699 depiction 12-annulene.svg.