25. Aromatic compounds

Question 1

What is the evidence for the delocalised model of benzene?

Answer 1

-The length of the carbon - carbon bonds is all the same length (in-between the length of a single and double bond)
-The enthalpy change of hydrogenation is less exothermic than expected.
-Benzene does not react with benzene to decolonise it.

Question 2

What are the reactants and conditions for forming nitrobenzene?

Answer 2

React benzene with HNO3. Use a H2SO4 catalyst and 50 degrees C.

Question 3

How do you nitrate benzene to get further substitution (1,3 dinitrobenzene)?

Answer 3

React benzene with HNO3. Use a H2SO4 catalyst at 70 degrees C.

Question 4

How is bromine halogenated?

Answer 4

A halogen carrier catalyst is needed - AlCl3, AlBr3, FeCl3, FeBr3

Question 5

What is the alkylation of benzene? And how is it done?

Answer 5

The substation of a hydrogen atom into the benzene ring by an alkyl group. This is achieved by reacting benzene with a haloalkane in the presence of AlCl3.

Question 6

What is the acylation of benzene?

Answer 6

This is when benzene reacts with acyl chloride in the presence of an AlCl3 catalyst to form an aromatic Ketone.

Question 7

Why is phenol classed as a weak acid?

Answer 7

When dissolved in water it partially dissociates into a phenoxide ion and a proton