Question

this compound not aromatic with explanationQ.46​plzx hepl miiii frnds

Answer 1

According to Huckels rule, conditions for aromaticity is:

1) the compound should exhibit cyclic resonance.

2) the compound should have 4n+2 pi electrons/ 2n+1 pi electron pairs.

All the above compounds have cyclic resonance. The difference lies in pairs Of pi electrons.

To count no. Of pi electron pairs:

1) count pi bonds taking part in resonance.

2) In heterocyclic compound, count no. Of lone pairs of hetero atom taking part in resonance.

3) For anionic compound, add no. Of negative charges contributing resonance. to the total pi electron pair counted.

So in compound A, There is 3 pi electron pairs(2 pi bonds and one lone pair of nitrogen). Since it has odd no. Of pi electron pairs it follows huckels rule and is aromatic.

In compound B, It has 3 pi electron pairs( 3 pi bonds. one lone pair of electron in Nitrogen doesnot take part in resonance.) Hence it is aromatic.

In compound C, It has 2 pi electron pairs( 2 pi bonds). Since it has even no. Of pi electron pairs it does not follow Huckels rule and is not aromatic. That is your answer.

In compound D, it has 3 pi electron pairs( 2 pi bonds and it has negative charge. So add 1). So it is again aromatic.