Huckel's Rule (4n+2)
- Thread starter CSade469
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Wikipedia pretty good: http://en.wikipedia.org/wiki/Hückel's_rule
A little hint: if the nitrogen or whatever in the ring has a lone pair of electrons on it, only count those electrons if the nitrogen or whatever DOES NOT have a double bond touching it.
if the N has a lone pair but also has one or two double bonds, DO NOT count them.
good luck
A little hint: if the nitrogen or whatever in the ring has a lone pair of electrons on it, only count those electrons if the nitrogen or whatever DOES NOT have a double bond touching it.
if the N has a lone pair but also has one or two double bonds, DO NOT count them.
good luck
Just to elaborate on the 2, 6, 10 ,14...
Like ak47 said sometimes you dont count the lone pairs other times you do. So you take all the pi electrons and lone pairs (when applicable to be included) and set them equal to 4n+2 electrons. For example the number 10 is a huckel number because 4n+2=10 n=2 and as long as n=0,1,2..(an integer) it passes the test.
Like ak47 said sometimes you dont count the lone pairs other times you do. So you take all the pi electrons and lone pairs (when applicable to be included) and set them equal to 4n+2 electrons. For example the number 10 is a huckel number because 4n+2=10 n=2 and as long as n=0,1,2..(an integer) it passes the test.
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Just because something passes huckel's rule doesn't mean it is always aromatic. You also must make sure it is planar.
Just to add: it has to be cyclic and conjugated also.
If the compound is neither anti-aromatic or aromatic, then it's got to be non-aromatic.
For a compound to be anti, these must happen.
1. Planar.
2. Conguated double bonds.
3. Cyclic.
4. Follows 4N instead of 4N+2 rule.
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how do we know whether something is planar or not?
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planar molecules are sp2.
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Yes. Aren't you impressed by my big brain?
I knew it!
Good luck on your DAT next week. You know Formosa Chang is rooting for you.
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Thanks hun.
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Quick Q....i know the criteria for Huckels rule, but one thing that is a thorn in my side is the substituent that is connected to the ring. Will that matter if it its planer or not? Of course it being not a ring. Basically if you have a benzene ring connected to a t-butile. Is it considered aromatic? I know its planer, all bond are SP2, N= 1. But the T-butile, does it have a say in the ring being aromatic or not?
the substituents don't matter unless they disrupt the cyclical conjugation of the ring causing a conformatinal change in its structure.
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I thought planar is aromatic, not anti aromatic.
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Both aromatic and anti-aromatic are planar. If its non planar its non-aromatic.
It has to first meet these 3 rules to be considered aromtic or anti-aromatic
1. Planar.
2. Conguated double bonds.
3. Cyclic.
If any of those are not met its non-aromatic
Then,
4n+2 = aromtic
4n = anti-aromatic
It has to first meet these 3 rules to be considered aromtic or anti-aromatic
1. Planar.
2. Conguated double bonds.
3. Cyclic.
If any of those are not met its non-aromatic
Then,
4n+2 = aromtic
4n = anti-aromatic
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Why is aniline aromatic according to Huckel's rule? When I draw the structure out, I see six pi electrons around the benzene ring, and 2 pi electrons on the nitrogen (which is sp2 hybridized). This gives me a total of 8 pi electrons.
With 8 pi electrons, I find that aniline is antiaromatic. Where am I going wrong??
With 8 pi electrons, I find that aniline is antiaromatic. Where am I going wrong??
