Aromatic and Anti-aromatic Compounds

What is the chemical formula for benzene, a compound whose structure was famously conceived by August Kekulé?

• C5H5

• C6H6

• C7H7

• C8H8

What is a key characteristic of the carbon-carbon bonds in a benzene ring?

• They alternate between long single bonds and short double bonds.

• They are all the same length, intermediate between single and double bonds.

• They are all single bonds, making the ring very flexible.

• They are all double bonds, making the ring very rigid.

Which of the following is NOT a characteristic of aromatic compounds?

• They are cyclic.

• They are planar.

• They have a continuous pi system.

• They always contain an odd number of pi electrons.

According to Hückel's Rule, a molecule is considered aromatic if its number of pi electrons equals 4n + 2, where 'n' is an integer. Which of the following numbers of pi electrons would make a molecule aromatic?

• 4

• 8

• 10

• 12

Pyridine can act as a base because it has a pair of electrons available to accept a proton. Why can't pyrrole do the same?

• Pyrrole's electrons are too small

• Pyrrole's electrons are already part of its stable ring structure

• Pyrrole has no available electrons

• Pyrrole is not a ring-shaped molecule

Cyclodecapentaene has a certain number of electrons that usually make a compound aromatic, but it is not aromatic. What is the main reason for this?

• Its ring is too small

• It is not flat

• It has too few carbon atoms

• It has too many single bonds

What is a key characteristic of anti-aromatic compounds?

• They are very stable

• They are very unstable

• They are always gases

• They are always solids

What combination of properties describes an aromatic compound?

• It is a ring shape, flat, has electrons that move freely, and follows a special electron count rule

• It is a straight chain, flat, has electrons that move freely, and follows a special electron count rule

• It is a ring shape, bumpy, has electrons that move freely, and follows a special electron count rule

• It is a ring shape, flat, has electrons that are fixed, and follows a special electron count rule