ketones

ketones

Suffix '-one'
1. Parent chain is longest unbranched Carbon chain
  1. C=O is numbered to show position so the smallest no. is used
Reacts
1. Different to alkenes as O in C=O is more elecronegative than C
  1. Creates a Dipole as bonded electrons are drawn towards O
2. Reduction
  1. Reduced to secondary alcohols by naBH4
    1. By neucleophillic Addition
      1. BH4- ion acts as hydride ion source (:H-)
        Electron defficient C+ in polar C=O gets attacked by :H-
        At same time C=O breaks producing a negatively charged intermediate
        Intermediate donates electron pair to a H from H2O
        This forms a dative covalent bond and a OH-
        The organic addition product is an alcohol
C-C=O
Aromatics
1. Pehnylethanone
Production
1. Oxidised from secondary alcohols, CANNOT be oxidised further
  1. Suitable oxidising agent acidified dichromate; H+/Cr2O7 2-
Tests
1. 2,4-DNP (Brady's reagent)
  1. Yellow or Orange precipitate is formed
    1. No precipitate formed with COOH or O=C-O
    2. Precipitate Is impure so is filtred and recrystallised to produce a pure sample
      1. Filtred again and left to dry
        Melting point is measured and recorded
        Melting point compared to known samples on a database
  2. Confirms C=O functional group
2. Tollens' Reagent
  1. No reaction indicates a Ketone is present
  2. Made by addition of NaOH(aq) to AgNO3(aq) until brown silver oxide precipitate is formed
    1. Dilute NH39aq) added until precipitate dissolves

Resource summary

	Created by lily anna stokes about 11 years ago