Topic 11 Amines

• What is a quaternary ammonium salt? [1]

  Has 4 amine groups attached
• What are used as cationic surfactants? [1]

  Quaternary ammonium salts
• The hydrocarbon chain of a quaternary ammonium salt will bind to non polar substances, whilst the cationic head will dissolve in water, so they’re useful hair products. The positively charged part will bind to negatively charged surfaces such as hair
• The more availability of lone pair of electrons means the stronger the base
• Amines act as a weak base because they accept protons
• Why do amines act as a weak base? [1]

  Because they accept protons
• FOr an amine there is a lone pair on the nitrogen which allows a coordinate bond to form to a H+ ion
• How can you reduce a nitrile to a primary amine? [2]

  Use lithium aluminium hydride (LiAlH4) in a non aqueous solvent followed by some dilute acid
• Because LiAlH4 is expensive, what is another method in which nitriles are reduced? [2]

  Using hydrogen gas with a metal catalyst such as platinum or nickel at a high temperature and pressure. This is called catalytic hydrogenation
• See notes for mechanism with nitriles
• Aromatic amines are produced by reducing a nitrogen compound, such as nitrobenzene
• How do you produce aromatic amines? [3]

  Heat mixture of nitro compound, tin metal and concentrated sulfuric acid HCl under reflux -making a salt

  to turn salt into aromatic amines you need to add an alkali like NaOH

  they’re useful compounds in organic synthesis and are used in lots of dyes and pharmaceuticals
• Amides contain the functional group - CONH2

  The carbonyl group pulls electrons away from the NH2 group, so amides behave differently from amines