Aromaticity
The special stability of planar cyclic molecules with a continuous, fully conjugated system of delocalised pi electrons.
Formula / equation
planar, cyclic, conjugated, 4n+2 π
Unit
kJ/mol
In depth
Aromatic compounds are far more stable than their conjugated open-chain analogues and undergo substitution rather than addition so as to preserve the delocalised system. Aromaticity also produces a characteristic downfield shift in NMR caused by the induced ring current.
Examples in the real world
Benzene, pyridine, furan and the purine and pyrimidine bases of DNA.