Aromatic compounds question

[Leester]

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Hey everyone. This is one of the questions from DAT bootcamp's question of the day series. I thought the only possible answer would be III. The answer turned out to be D (I and III). I thought compound 1 would not be aromatic because is is non-planar (Above 7 Carbons). Is compound 1 considered planar?

Thank you

 

[Myce]

I think the reason the first one is considered aromatic is because it follow's Huckel's Rule of 4n+2 (there are 14 pi electrons 4(3) + 2 = 14), is in a conjugated cyclic system, so it's most likely planar.

 

[SLDENTAL]

I talked to my orgo teacher about this question and he said it is a bad question b/c can be interpreted in different ways for which is aromatic or not bc not because like u said it could be non planar

 

[Leester]

Ah I see. I just remember in Chad's videos he said something like anything > 7 carbons in structure is non planar so this question was confusing. Appreciate it.

 

[Ari Rezaei]

Ah I see. I just remember in Chad's videos he said something like anything > 7 carbons in structure is non planar so this question was confusing. Appreciate it.

Considering anything over 7 carbons as non planar and not aromatic is an OK way to think about it in a test prep sense, but there are quite a few compounds that are aromatic with more carbons. But yes, if you have 8 or 10 carbons then it won't be aromatic, so those are good to know and what the ADA will likely test on the planar concept of aromaticity.

Also, compound 1 is an aromatic annulene, it's large enough to accommodate all the double bonds and still be planar. You can see more information here: http://en.wikipedia.org/wiki/Cyclotetradecaheptaene