Question

Indicate whether each of the structure is aromatic, nonaromatic, or antiaromatic. Treat all structures as planar.

Indicate whether each of the structure is aromatic, nonaromatic, or antiaromatic. Treat all structures as planar.

Answer 1

Rules for Aromaticity, Antiaromaticity and Nonaromaticity

A molecule is aromatic if:

- It must be a PLANAR moelcule, i.e. 2-D; should not have a single sp3 hybridized carbon

- Must follow Huckel's Rule, which state that the conjugated electrons must fit 4n+2 rule... that is

n (0,1,2,3,4...) then, total electrons E = (2, 6, 10, 14, 18...)

- Must be CYCLIC, so the electrons can actually flow in the "ring"

- Most of the species must be Sp2 hybridized (not sp3)

An antiaromatic species is similar to aromatic... it should only fail in:

- It must be a PLANAR moelcule, i.e. 2-D; should not have a single sp3 hybridized carbon

- Must NOT follow Huckel's Rule, which state that the conjugated electrons must fit 4n+2 rule... that is

n (0,1,2,3,4...) then, total electrons E = (2, 6, 10, 14, 18...); if this is anti aromatic, the lone pairs should be all but those set of numbers...

- Must be CYCLIC, so the electrons can actually flow in the "ring"

- Most of the species must be Sp2 hybridized (not sp3)

Finally... NON-Aromatic are those that will fail at least other than huckels rule:

i.e.

If this molecule is NOT 2-D, i.e. not planar, then this is antiaromatic

If this is not a cycle, then this is NOT aromatic

There is any SP or SP3 hybridized...

Knowing this:

A)

this is planar, has 2 electrons pair, is cyclic

this must be aromatic

B)

this is not cyclic therefore non-aromatic

C)

This is planar

total electrons in ring = 6

this applies for huckel rule

therefore, must be aromatic

D)

this is planar

it is cyclic

total double bonds = 10, therefore 20 electrons

huckel rule

4n +2 = if n = 4, then e = 18

this fails huckel rule, so it must be ANTIaromatic

E)

not cyclic

this is non-aromatic