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Compound A

In the following compound (Pyrene) why isn't Huckle's (4n+2) rule applicable? I do know it is applicable to only mono-cyclic ring systems but what changes when there are more than 3 fused rings?

Edit:

A similar question has been posted previously but that doesn't mention as to why only the peripheral bonds are to be considered.

J_B892
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  • @thewitness please do see the edit – J_B892 Nov 07 '18 at 12:01
  • That is because the double bond in the centre doesn't take part in resonance. It is quite similar to the lone pair in pyridine and the "second" lone pair in furan where we don't consider them as a part of π electrons while applying Haeckel's Rule. We require a complete conjunction to classify a compound into aromatic or non aromatic. In case there is no complete conjugation, it is non aromatic. – user600016 Nov 07 '18 at 12:24
  • So in any of such compounds the double bonds not along the periphery do not involve in resonance? – J_B892 Nov 07 '18 at 12:26
  • It depends on whether or not it can participate in resonance. – user600016 Nov 07 '18 at 12:29
  • So the peripheral rule isn't applicable everywhere? – J_B892 Nov 07 '18 at 12:37
  • @thewitness " double bond in the centre doesn't take part in resonance" -it's impossible, also its taking part in resonance isn't a problem at all. – Mithoron Nov 08 '18 at 23:28
  • Huckle's rule is applicable to specific rings not whole compounds. If compound has at least 1 aromatic ring, then it's aromatic. – Mithoron Nov 08 '18 at 23:30

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