Arenes- 18.1

Question 1

Molecular formula of benzene

Answer 1

C6H6

Question 2

Structure of benzene:

Answer 2

• each C atom is bonded to 2 other C atoms and one H atom by single covalent sigma bonds.
  > this leaves 1 unused electron on each C atom in a p orbital, perpendicular to the plane of ring
  > the 6 p electrons are delocalised in a ring structure above and below the plane of carbon atoms

Question 3

In 1865, kekule suggested that the structure of benzene consisted of alternate single and double covalent bonds between the carbon atoms.
WHY IS THIS STRUCTURE INCORRECT?

Answer 3

This structure isn’t correct as it suggests that all the C-C bonds are the same length

Question 4

Benzene’s reactions are usually…

Answer 4

Electrophillic substitution

Question 5

Why doesn’t benzene generally undergo addition reactions?

Answer 5

Because addition reactions would involve breaking up the delocalised system

Question 6

Why doe benzene attract electrophiles?

Answer 6

Because it has a high electron density

Question 7

In other molecules the benzene ring can be regarded as a substituent side group on another molecule, like alkyl groups are. The C6H5- group is known as the…

Answer 7

phenyl group
E.g: phenylamine