1. AS Chemistry
OXIDATION OF ALCOHOLS

2. NOT SIGNIFICANT for TERTIARY alcohols! for SECONDARY alcohols
OXIDATION OF ALCOHOLS
Oxidised to
aldehydes and acids
or ketones
NOT SIGNIFICANT for TERTIARY alcohols!
for PRIMARY alcohols
for SECONDARY alcohols
-CH2OH
-C-CH(OH)-C-
NB Oxidant
= hot acidified Cr2O72-
[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. C H OH C H OH C OH    + [O] + [O] + [O] C O H C O + H2O + H2O
PRIMARY
SECONDARY
TERTIARY C H OH C H OH C OH   
+ [O]
+ [O]
+ [O] C O H C O
NO SIGNIFICANT OXIDATION
+ H2O
+ H2O
- no C–H bond
Aldehyde
Ketone
Any oxidation that does occur involves breaking C-C bonds  loss of original structure.
+ [O] 
+ [O]  C O OH
NO FURTHER OXIDATION
Acid
- no C – H bond

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

5. Click here for Distillation and Reflux Apparatus
Controlling Oxidation Products
To Maximise the Production of an ALDEHYDE
To Maximise the Production of an ACID or a KETONE
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 :
Methanol
Propan-2-ol
Propan-1-ol
Pentan-3-ol
2-Methyl-butan-2-ol
Methanal
Methanoic acid
Methanone
None
Propanal
Propanoic acid
Propanone
Pentan-3-al
Pentan-3-oic acid
Pentan-3-one
2-Methylbutanal
2-Methylbutanoic acid
2-Methylbutanone

7. The End

8. Distillation
Reflux

9. CORRECT – WELL DONE!
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10. NOT CORRECT – TRY IT AGAIN
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