BASES

• WHY CAN AMINES REACT AS BASES?

  can accept protons and are therefore Bronsted-Lowry bases
• WHAT TYPE OF SALTS ARE AMMONIUM SALTS?

  water-soluble, ionic salts
• HOW DOES AMINE REACT WITH ACIDS?

  produce salts

  e.g. ethylamine reacts with dilute hydrochloric acid to form ethylammonium chloride
• HOW DOES PHENYLAMINE REACT WITH ACIDS?

  dissolves in excess hydrochloric acid to produce phenylammonium chloride
• WHAT HAPPENS WHEN AN AMMONIUM SALT IS REACTED WITH A STRONG BASE?

  proton removed from salt and the insoluble amine is regenerated
• EXAMPLE OF A STRONG BASE?

  NaOH
• WHAT DOES BASE STRENGTH DEPEND ON?

  how readily it will accept a proton using its lone pair
• EFFECT OF ALKYL GROUPS?

  • release electrons towards N atom
  • inductive effect
  • increases electron density
  • better electron donors
  • primary alkylamines stronger bases than ammonia
  • secondary alkylamines stronger bases than primary alkylamines
  • tertiary alkylamines not stronger bases than secondary alkylamines as less soluble in water
• EFFECT OF ARYL GROUPS?

  • withdraw electrons from N atom
  • as lone pair overlaps with delocalised system
  • N is a weaker electron pair donor
  • arylamines are weaker bases than ammonia
• BASE STRENGTHS?

  alkylamines > ammonia > arylamines