MolSynapsequestion bank
MolSynapse / Question bank / General Organic Chemistry I: Electronic Effects / Aromatic, antiaromatic and non-aromatic rings
JEE Main levelSingle correct optionDifficulty 2 of 3g1242

The compound shown behaves as an ordinary polyene rather than as a cyclic conjugated antiaromatic system because

  1. Ait is planar and has 6 pi electrons
  2. Bit contains sp3 carbon atoms
  3. Cit adopts a non-planar tub shape, which prevents cyclic delocalisation of the 8 pi electrons
  4. Dit is planar and aromatic because it has 8 pi electrons

Answer: C

The compound shown is cyclooctatetraene. A planar ring would have 8 pi electrons and be antiaromatic, so the molecule avoids this by adopting a non-planar tub shape. The p orbitals then overlap poorly across the ring and the double bonds behave as in a normal polyene.
Practice General Organic Chemistry I: Electronic Effects More on Aromatic, antiaromatic and non-aromatic rings
Previous questionNext question

More questions on Aromatic, antiaromatic and non-aromatic rings