Give an explanation for each of the following observations:(a) Compound A has six π electr...

Give an explanation for each of the following observations:

(a) Compound A has six π electrons but is not aromatic.

(b) Compound B has six π electrons but is not aromatic.

(c) Compound C has 12 π electrons and is aromatic.

Sample Solution (a) Cycloheptatriene (compound A) is not aromatic because, although it does contain six π electrons, its conjugated system of three double bonds does not close on itself—it lacks cyclic conjugation. The CH2 group prevents cyclic delocalization of the π electrons.