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OXIDATION OF ALCOHOLS

AS Chemistry. OXIDATION OF ALCOHOLS. NOT SIGNIFICANT for TERTIARY alcohols!. for PRIMARY alcohols. for SECONDARY alcohols. OXIDATION OF ALCOHOLS. or ketones. Oxidised to. aldehydes and acids. -CH 2 OH. -C-CH(OH)-C-. NB Oxidant. = hot acidified Cr 2 O 7 2-. [dichromate(VI)] ion].

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OXIDATION OF ALCOHOLS

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  1. AS Chemistry OXIDATION OF ALCOHOLS

  2. NOT SIGNIFICANT for TERTIARY alcohols! for PRIMARY alcohols for SECONDARY alcohols OXIDATION OF ALCOHOLS orketones Oxidised to aldehydes and acids -CH2OH -C-CH(OH)-C- NB Oxidant = hotacidifiedCr2O72- [dichromate(VI)] ion] Provided by mixture of potassium dichromate(VI), K2Cr2O7, and excess dilute sulphuric acid, H2SO4. Oxidant is represented by : [O] Orange Cr2O72- reduced to green Cr3+

  3. PRIMARY SECONDARY TERTIARY H C C C C C C C C H H C OH OH OH C C O O H C C C + [O] + [O]   OH C C O    + [O] + [O] + [O] NO SIGNIFICANT OXIDATION - no C–H bond + H2O + H2O Any oxidation that does occur involves breaking C-C bonds loss of original structure. Aldehyde Ketone NO FURTHER OXIDATION - no C –H bond Acid

  4. What are the oxidation products of : 1. Ethanol? 2.  Methyl-propan-2-ol? 3.  Butan-2-ol ? CH3CH2CH(OH)CH3 CH3CH2OH CH3C(CH3)(OH)CH3 Primary Tertiary Secondary Ethanal 1.CH3CH2OH + [O]  CH3CHO + H2O CH3CHO + [O] Ethanoic acid  CH3COOH 2.No significant oxidation 3. CH3CH2CH(OH)CH3 + [O]  CH3CH2COCH3 + H2O Butanone

  5. Controlling Oxidation Products This is PARTIAL oxidation This is FURTHER oxidation Use only molar proportions of dichromate and acid Use excess of dichromate and acid Use minimum contact time between alcohol and oxidant by use of immediate distillation Use maximum contact time between alcohol and oxidant by use of reflux Add acidified dichromate to the alcohol to avoid the presence of excess oxidant Pre-mix acidified dichromate and alcohol to ensure excess oxidant at all times Click here for Distillation and Reflux Apparatus

  6. Click on the options to select the possible oxidation products (MAY BE MORE THAN ONE) derived from :

  7. The End

  8. Distillation Reflux

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