What is the requirement for "aromaticity"? Why is cyclohexane non-aromatic?

1 Answer
anor277
Jul 7, 2016

A requirement for aromaticity is 4n+2 pi electrons

Explanation:

Benzene, C_6H_6, certainly meets this criterion; so does pyridine, C_5H_5N, and pyrrole, C_4H_5N, and furan, C_4H_4O, and thiophene, C_4H_4S. Cyclohexane has no pi electrons, and cyclohexene and cyclohexadiene have 2 and 4 pi electrons respectively.

The 5-membered ring aromatic heterocycles are so-called pi-"excessive" species, whose reactivity in electrophilic substitution is enhanced.

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