Benzene

Benzene

1. Aromatic/Arene

   • aliphatic : straight or branched chain organic substances
   • aromatic or arene: includes one or more ring of six carbon atoms with delocalised bonding

2. Delocalised Electron structure increases stability, shown by Enthalpy of hydrogenation.

   • Is a planar molecule with a bond length between C=C and C-C

3. Reactions are usually electrophilic substitution

   • Does not generally undergo addition reactions because these would involve breaking up the delocalised system. Benzene has a high electron density and so attracts electrophiles.
   • Nitration Of Benzene
     • Conc H2SO4/HNO3
       • H2SO4 + HNO3 → HSO4 – + NO2 + + H2O
     • Important step in synthesising useful compounds e.g. explosive manufacture (like TNT, trinitrotoluene/ 2,4,6- trinitromethylbenzene) and formation of amines from which dyestuffs are manufactured.
   • Friedel Crafts Acylation
     • Acyl Chloride and AlCl3
     • Adds a reactive functional group to Benzene ring ,C=O

4. Reduction of nitrobenzene to phenylamine

   • Tin/Hcl or H2/Nickel