question_answer 77)

  Which of the following compounds are aromatic according to Huckel?s rule? (a)                  (b)             (c)               (d) (e)                 (f)

Answer:

  (A) The compound has \[8\pi \]-electrons, it will be non aromatic; both rings are non-benzenoid. (B)It is aromatic. It has \[6\pi \]-delocalised electrons\[(4\pi {{e}^{-}}+2\] lone pair electron) (C) 6\[\pi \]-electrons but not in the ring hence it is non-aromatic (D) 10\[\pi {{e}^{-}}\] obeying Huckel rule. It is aromatic. (E) one ring has \[6\pi {{e}^{-}}\]. It is therefore aromatic. (F) It has \[14\pi \]-electrons in conjugation and in the ring. Huckel rule is verified. It will be aromatic provided it has planar ring.