Module 6.2.1- Amines

• Primary Amine


  An amine where the nitrogen atom is attached to one alkyl chainR-NH2

  
• Secondary Amine


  An amine where the nitrogen atom is attached to two alkyl chainR-NH-R

  
• Tertiary Amine

  An amine where the nitrogen atom is attached to three alkyl chainR3N

  
• Why can amines act as bases?


  The lone pair of electrons on the nitrogen atom can accept a proton forming a dative covalent bond
• Naming amines example

  2-aminobutaneif the amine group was at the end (carbon 1/4) then the name would be butylamine

  
• Amine + Acid (e.g. HCl or H2SO4)

  Ammonium salt

  
• Formation of primary amines


  React with a haloalkane with ammonia to form an ammonium saltAqueous alkali then generates the amine from the saltEthanol used as the solvent and excess ammonia used
• Why is ethanol used as a solvent in preparation of primary amines?


  prevents the substitution of the haloalkane by water to form alcohols
• Why is excess ammonia used in preparation of primary amines?


  reduces further substitution of the amine group to form secondary and tertiary amines
• Formation of secondary and tertiary amines

  1) add primary amine to haloalkane to form an ammonium salt

  2) react product with sodium hydroxide

  3) tertiary amines formed by further reaction of the secondary amine

  
• Preparation of aromatic amines


  Reduction of nitrobenzene Heated under reflux with Tin and Hydrochloric acid Forms ammonium salt which is then reacted with excess NaOH Tin/HCl act as a reducing agent