Anti-Aromatic confusion

[makwendo]

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The Kaplan white book (same as the blue book) classifies the following as anti-aromatic


An 8 carbon ring with 4 alternating double bonds (8pi electrons)


However, topscore says this molecule isn't anti aromatic


who is correct?

 

[organichemistry]

The Kaplan white book (same as the blue book) classifies the following as anti-aromatic


An 8 carbon ring with 4 alternating double bonds (8pi electrons)


However, topscore says this molecule isn't anti aromatic


who is correct?

1,3,5,7-tetraoctene is not aromatic.

 

[BeatValley]

The Kaplan white book (same as the blue book) classifies the following as anti-aromatic


An 8 carbon ring with 4 alternating double bonds (8pi electrons)


However, topscore says this molecule isn't anti aromatic


who is correct?

Anti aromatic is 4n Pi electrons, Non aromatic is everything else that isn't aromatic (non cyclic, non conjugated, non 4n or 4n+2), and aromatic is 4n+2 pi electrons.

 

[makwendo]

Anti aromatic is 4n Pi electrons, Non aromatic is everything else that isn't aromatic (non cyclic, non conjugated, non 4n or 4n+2), and aromatic is 4n+2 pi electrons.

Exactly, that's what's getting me stumped here. The molecule in question is cyclic, conjugated and has 4n pi electrons.But from what organicchemistry is saying, it's just plain non aromatic and not anti aromatic...


I don't want to start any aromaticity argument here, basically, apart from the definition beatvalley gave above, are there any exceptions that I need to know just for the DAT....

 

[BeatValley]

Exactly, that's what's getting me stumped here. The molecule in question is cyclic, conjugated and has 4n pi electrons.But from what organicchemistry is saying, it's just plain non aromatic and not anti aromatic...


I don't want to start any aromaticity argument here, basically, apart from the definition beatvalley gave above, are there any exceptions that I need to know just for the DAT....

There are no exceptions that I know of, but remember that lone electrons can join the pi system. So if you have a cyclo hexane with 2 double bonds and a negatively charged carbon with lone electron pairs, the lone pairs are considered part of the pi system, so its considered aromatic (4n+2). As far as I know, any molecule thats cyclic, conjugated, and has 4n pi electrons is anti aromatic. If theres some exception to the rule it wouldn't be on the DAT.

 

[apbshah]

I believe it has something to do with not being planar, as in on the same plane. If the pi electrons are not on the same plane, it can not be considered anti-aromatic or aromatic, even if its conjugated double bond (I'm not sure, if that's possible with conjugated double bonds, but still!) Its simply non-aromatic. Hope that helps! (Hope thats right!!! 😉)