The criteria for aromaticity is presence of_________?
Correct answer: D. Presence of 4n+2π electrons
- A. Unsaturations
- B. Cyclic structure
- C. Presence of 4nπ electrons
- D. Presence of 4n+2π electrons
Explanation
Aromatic compounds require a cyclic, planar, continuously conjugated system containing 4n + 2 pi electrons, according to Huckel's rule. This electron count permits extra resonance stabilisation, so option d is the intended criterion. The likely distractor is option c, 4n pi electrons, which generally gives antiaromatic destabilisation rather than aromatic stability.
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About Benzene and Aromatic Compounds
Benzene has a planar ring of delocalised π electrons, giving aromatic stability and equal carbon-carbon bond lengths. The topic covers resonance, electrophilic substitution reactions such as nitration, halogenation, sulphonation and Friedel-Crafts reactions, along with substituent effects and the distinction between substitution in benzene and addition in ordinary alkenes.
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