Aromatic chemistry

• Chemical formula for benzene is C6H6
• Benzene is drawn as a hexagon with a circle inside it.

  
• Naming with benzene

  Benzene would be used as a suffix for examples such as Chlorobenzene or Nitrobenzene (NO2 on the benzene) or it could be used as a prefix but it's name changes to phenyl e.g. phenylethene
• Common benzene derivates

  This would be named trinitrotoluene or known as TNT.

  Used in explosives

  
• Common benzene derivates

  Known as Azo

  Used in Dyes

  
• Naming benzene derivates

  Common name : polystyrene

  Used in packaging

  
• Naming benzene derivates

  Common name: Aspirin

  Used in painkillers

  
• Common benzene derivates

  Common name: Paracetamol

  Used in painkillers

  
• Benzene can undergo hydrogenation using a nickel catalyst to form cyclohexane
• Benzene has a lower enthalpy change then expect because of the delocalised electrons due to the overlapping p orbitals making it more stable
• Unlike alkene it doesn't decolourises bromine water or take part in another electrophilic addition reactions because it's too stable
• Benzene is found to be symmetrical this was found using X-ray crystallography
• Benzene has the same boiling point as hexane because they both have 6 carbons but it has a higher melting point because its planar so the benzene rings stack closely together
• Nitration

  Benzene can go through electrophilic substitution to form nitrobenzenes.

  Conditions

  • High temperature
  • H2SO4 catalyst
  • HNO3 as the reagent
• Electrophilic substitution

  H2SO4 + HNO3 --> HSO4- + H2NO3+

  As the stronger acid releases more H+

  Then

  H2NO3+ dissociates into NO2+ and H20
• Electrophilic substitution of benzene

  First a curly arrow from the circle in the benzene goes to the NO2+. This causes the bond between the hydrogen and benzene to go to the circle to make it stable. The H+ ion would be used to reform the catalyst

  
• Friedel-craft acylation pt2

  The mechanism is electrophilic substitution

  RCOCl + AlCl3 --> AlCl4- + RCO+

  The electrophile would be RCO+.

  The electrons from the benzene ring goes to it and then the hydrogen is removed and used to reform catalyst

  
• Nitroarenes going through reduction

  Reagent is Tin and HCl

  
• Effect of delocalisation on side groups with lone pairs

  Chlorobenzene

  • The c-cl bond is made stronger so typical haloalkane substitution and elimination does not occur and will repel nucleophiles

  Phenol

  • Delocalisation makes the C-O bond stronger and the O-H bond weaker so it won't act like an alcohol and its more acidic and doesn't oxidise.

  Phenylamine

  • Less available to accept a proton