How to judge aromaticity

Judging whether organic matter is aromatic according to Hooker's law.

Huckel's law states that a monocyclic compound has a planar delocalization system as long as its π electron number is 4n+2 (n = 0, 1, 2,3, ... n is an integer). Where n refers to the number of groups of combined bonded and unbonded tracks.

Benzene has six π electrons, which conforms to the 4n+2 law, and all six carbon atoms are on the same plane, so benzene has aromaticity. The π electron number of cyclobutadiene and cyclochlorobutene does not conform to 4n+2 law, so they have no aromaticity. Aromatic hydrocarbons without benzene rings are called non-benzene aromatic hydrocarbons, including some cyclic polymers and aromatic ions.

The essence of aromaticity

Aromaticity is characterized by easy electrophilic substitution and difficult addition and oxidation reactions. Aromaticity is characterized by a ring-shaped closed yoke system, π electrons are highly delocalized, have delocalization energy, and the system energy is low and relatively stable. Whether a substance is fragrant or not can be judged according to Hooker's Law.

Anyone who conforms to Huck's rule is fragrant; Aromatic compounds without benzene rings are called non-benzene aromatics, including some cyclic polyenes and aromatic ions.