9. Benzene

Question 1

What does an aromatic compound refer to?

Answer 1

Benzene and its structural relatives

Question 2

How does the stability of cyclohexanes change with increasing c=c double bonds?

Answer 2

As the number of double bonds are added, stability of cyclohexane increases (benzene is the most stable)

Question 3

What is the reactivity of benzene?

Answer 3

Compared to alkenes it is not very reactive.

No addition reaction, substitution only with catalyst

Question 4

What is the resonance stabilisation of benzene?

Answer 4

• The real structure of benzene is a hybrid of the resonance forms
• The pi electrons are not localised between specific carbon atoms, they are delocalised
• The circle represents the delocalised electrons but it doesn’t indicate how many pi electrons are in the ring

Question 5

What is the stability difference between the resonance hybrid and individual resonance forms?

Answer 5

The resonance hybrid is more stable than individual resonance forms

Question 6

What are the three requirements for aromatic?

Answer 6

• Cyclic
• Conjugated (alternating double and single bonds)
• Planar

Question 7

What is the Huckel rule?

Answer 7

4n + 2= number of pi electrons, and must be an integer

Question 8

For disubstituted benzenes, what does ortho mean?

Answer 8

1,2-disubstituted

Question 9

For disubstituted benzenes, what does meta mean?

Answer 9

1,3 disubstituted

Question 10

For disubstituted benzenes, what does para mean?

Answer 10

1,4 disubstituted