organic qualitative analysis

• Test and observation for an alkene


  Add bromine water.

  Bromine water decolourised
• Test and observation for a chloroalkane


  Add aqueous silver nitrate and ethanol

  Warm to 50°C

  White precipitate forms
• Test and observation for a bromoalkane


  Add aqueous silver nitrate and ethanol

  Warm to 50°C

  Cream precipitate forms
• Test and observation for a iodoalkane


  Add aqueous silver nitrate and ethanol

  Warm to 50°C

  Yellow precipitate forms
• Test for a carbonyl (aldehyde/ketone)


  Add 2,4-DNP

  Orange precipitate forms
• Test for an aldehyde


  Add ammoniacal silver nitrate solution/Tollens'

  Heat

  Silver mirror forms
• Test for primary and secondary alcohols


  Add acidified dichromate(VI) ions

  Heat

  Orange to green colour change
• Test for a carboxylic acid


  Add sodium carbonate solution

  Bubbles/effervescence
• Test for a phenol


  Add bromine

  Bromine decolourised and a white precipitate forms

  or

  Test pH below 7 to show acidic

  Add sodium carbonate and no bubbles should be produced
• Test to confirm the identity of a carbonyl


  Add 2,4-DNP

  Purify precipitate by recrystallisation

  Measure melting point of purified 2,4-DNP derivative

  Compare to known data values
• Description of a primary alcohol


  Hydroxyl group is bonded to a C which has one carbon group and two hydrogens directly attached
• Description of a secondary alcohol


  Hydroxyl group is bonded to a C which has two carbon groups and one hydrogen directly attached
• Description of a tertiary alcohol


  Hydroxyl group is bonded to a C which has three carbon groups directly attached