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MSc44

this may be a dumb question but how do you know if a ring structure is planer just by visualization. you need to know this if you want to determine if its aromatic or not, besides huckels rule.

is there somthing to look for right off the bat to know if its planer or not
 

jmart

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yes, up to six membered rings are planar, 7 and above is not. However, bicyclic rings are ok, like napthalene.
 

MahSpoon

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jmart said:
yes, up to six membered rings are planar, 7 and above is not. However, bicyclic rings are ok, like napthalene.
It is possible to have planar aromatics that are 7 (trophylium cation) and 8 member rings (cyclooctatetraene dianion)

You should basically see if it can do 4n+2, if so then it will be aromatic and thus planar since it is more stable.

In terms of anti-aromatic...if it is 4n and can pucker then it will. If it is forced to be planar (3 or 4 member ring) then it will be anti-aromatic.
 
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MSc44

MahSpoon said:
It is possible to have planar aromatics that are 7 (trophylium cation) and 8 member rings (cyclooctatetraene dianion)

You should basically see if it can do 4n+2, if so then it will be aromatic and thus planar since it is more stable.

In terms of anti-aromatic...if it is 4n and can pucker then it will. If it is forced to be planar (3 or 4 member ring) then it will be anti-aromatic.


is that the system you use when approached by an aromatic problem, how likely is it that there will be an acception on the mcat
is it safe to just look for 4n+2

i know there can be very large rings that can be aromatic. I looked in my text. SO im trying to figure out a clear and cut system to get me the right answer every time.
 

QofQuimica

Seriously, dude, I think you're overreacting....
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MSc44 said:
this may be a dumb question but how do you know if a ring structure is planer just by visualization. you need to know this if you want to determine if its aromatic or not, besides huckels rule.

is there somthing to look for right off the bat to know if its planer or not
http://forums.studentdoctor.net/showpost.php?p=3912139&postcount=10

Follow the rules in order. If you're not sure about planarity, but it's a ring and every atom has a p-orbital on it, then look at the number of pi electrons.
 
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