Question 1
Question 2
Question 3
Question 4
Answer to question 1
Both A and B are aromatic
tip: also considering the pi electrons of O atoms. total pi electrons 4n + 2 = 10. where n = 2. Thus, B is aromatic also.
Answer to question 2
Answer to question 3
Whether the given structures aromatic or not has to be identified.
The correct option is:-
(D) Both A and B are aromatic.
Both the structures are cyclic and planar.
They also satisfies the huckel’s rule for aromaticity as it has (4n+2)π electrons(4n+2)π electrons.
Therefore, they are aromatic in nature.
Answer to question 4
Part 1
Compound (a):
The ring has complete cyclic conjugation and the total number of pi electrons in the ring is 10 which follows the standard of 4(2) + 2.
Since the total number of pi electrons in a ring is of type 4n+2, n being an integer, the compound is aromatic.
Compound (b):
The ring has complete cyclic conjugation and the total number of pi electrons in the ring = 16 = 4(4)
Since the total number of pi electrons in the ring is of type 4n, n being an integer, we might think that the compound is anti-aromatic.
But it’s not the case. This compound is called pyrene, and it’s aromatic.
This is because anti-aromatic compounds are very unstable, and so if the ring can somehow convert that compound into a non-aromatic or aromatic compound (by stopping one double bond from doing resonance), it will do so.
This is because, by resonance, the compound goes into this form
Now, the double bond in the middle won’t do resonance, and so only 14 electrons resonate. Do remember, that complete peripheral conjugation is required for aromaticity.
As a rule, remember, fused benzene rings forms aromatic compound only, even if Huckel’s rule seems not to be followed.
So, the answer is option (c).
