18. Aromaticity

Make a model of cyclooctatetraene in the tub conformation. Draw this conformation, and estimate the angle between the p orbitals of adjacent pi bonds.

Explain why each compound or ion should be aromatic, antiaromatic, or nonaromatic.

(d)

(e)

(f) the [20]annulene dication

Despite having only sp²-hybridized carbons and having 10 electrons (4n + 2) , the annulene shown is not aromatic. Why?

Classify the following compounds as aromatic, antiaromatic, or nonaromatic.

(a)

(b)

Explain why each compound or ion should be aromatic, antiaromatic, or nonaromatic.

(a)

(b)

(c)