Reactions of benzene

• The nitration of benzene occurs when NO2+ ions act as an electrophile to benzene, taking an electron from the ring to form a single bond between the carbon and the NO2 group.
• The reaction to produce NO2 for electrophilic substitution of benzene

  Occurs at 50 degrees

  
• Benzene is a stable molecule due to its ring of delocalised electrons. This means it primarily undergoes substitution reactions.
• What are the three steps of the nitration of benzene?

  1. The production of the electrophile using a sulfuric acid catalyst
  2. Electrophilic Substitution
  3. Reformation of catalyst
• What are the steps in the halogenation of benzene?

  1. Making the electrophile using AlX3 or FeX3
  2. Electrophilic substitution mechanism
  3. Reformation of catalyst
• Below is the mechanism for the electrophilic substitution of benzene.

  A) E+

  B) E

  C) H+

  D) E

  
• Friedel-Crafts reactions attach subtituents to benzene rings. There are two types, Alkylation and Acylation, both of which follow electrophilic substitution.
• Friedel-Crafts Alkylation is used to substitute an alkyl group onto a benzene ring to produce an alkyl arene.

  It is carried out by reacting benzene with a chloroalkane under reflux with a halogen containing catalyst i.e, AlCl3 or FeCl3
• Friedel-Crafts substitutes an acyl group (RC=O) onto a benzene ring producing a phenylketone.

  It is carried out by reacting benzene with an acyl chloride under reflux in the presence of a halogen containing catalyst.
• What is the mechanism for acylation of benzene?

  Mechanism for Alkylation use AlCl3

  
• What is the mechanism for Acylation of benzene?

  Acylation of benzene with AlCl3 as a catalyst

  
• What is meant by an ortho-benzene?

  When function groups bonded to the benzene ring are bonded to adjacent carbons I.e 1,2-methyl benzene
• What is meant by meta-benzene?

  when two functional groups on a benzene ring are separated by a single carbon I.e 1,3-methylbenzene
• What is meant by para- benzene?

  Two functional groups bonded to a benzene ring and are on opposite carbons.
• Electron donating groups are 2-4-6 directing

  Electron withdrawing groups are 3-5 directing