
Aromatic compounds are cyclic, planar and must obey Huckel’s rule i.e. molecule must have 4n+2 pi-electrons where n is an integer (i.e. n=0,1,2,3,4…etc.). The compound B follws the Huckel's rule. The acid-base reactions fast reactions. Compound (A), also called squaric acid is a strong acid. So, above reaction proceeds very fast. All C−C bond lengths in (B) are same due to resonance. (A) shows tautomerism. A
