1. Redox reactions

2. Redox reactions of primary
alcohols



Primary alcohols react with oxidising agents
such as potassium manganate(VII) or
sodium dichromate(VI), forming the
corresponding aldehyde
For example, ethanol reacts forming ethanal
Ethanal is also formed in the metabolism of
ethanol in the human body

3. Reaction of ethanol with sodium
dichromate(VI)

4. Reaction of ethanol with sodium
dichromate(VI)



This reaction is used in the preparation of
ethanal
Reaction conditions: heat, excess ethanol,
acidified sodium dichromate(VI) solution
The aldehyde is distilled off as it is formed in
order to prevent further oxidation to ethanoic
acid

5. Preparation of ethanal

6. Oxidation of primary alcohols

Primary alcohols such as ethanol are
oxidised to the corresponding aldehydes,
which can be further oxidised to the
corresponding carboxylic acids.

7. Oxidation of ethanol
H
H
H
C
C
H
OH
H
+
H
Na2Cr2O7 / H
H
C
H
O
C
H
Na2Cr2O7 / H+
H
H
C
H
O
C
OH

8. Reaction of ethanol with sodium
dichromate(VI)



This reaction is used in the preparation of
ethanoic acid
Reaction conditions: heat, excess acidified
sodium dichromate(VI) solution
The reaction mixture is refluxed in order to
bring about oxidation to ethanoic acid

9. Preparation of ethanoic acid
Reflux
followed by
Distillation

10. Oxidation of secondary alcohols


Secondary alcohols such as propan-2-ol are
oxidised to the corresponding ketones, such
as propanone
Unlike aldehydes, ketones are not easily
oxidised, and so no further oxidation takes
place

11. Oxidation of propan-2-ol
OH
O
+
H3C
C
CH3
H
Na2Cr2O7 / H
H3C
C
CH3

12. Combustion of organic
compounds



Most organic compounds burn in air, forming
carbon dioxide and water
The structure of the compounds’ molecules
is completely destroyed, with the carbon and
hydrogen atoms in each molecule being
oxidised
Combustion is exothermic, and ethanol is
used as a fuel where it can be produced
cheaply

13. Non-flammable organic
compounds



Fully halogenated alkanes such as
bromochlorodifluoromethane are nonflammable
Because of this they can be used in fire
extinguishers and as flame retardants
For environmental reasons, the use of many
of these substances is being phased out

14. Reduction of aldehydes and
ketones


Aldehydes and ketones can be reduced to
the corresponding alcohols, using hydrogen
passed over the heated surface of a nickel
catalyst
For example, ethanal is reduced to ethanol

15. Reduction of ethanal to ethanol

16. Reduction of propanone to
propan-2-ol