Primary alcohols like ethanol can be oxidized to aldehydes using oxidizing agents such as potassium manganate(VII) or sodium dichromate(VI). For example, ethanol reacts to form ethanal. Ethanal is also produced when ethanol is metabolized in the human body. Sodium dichromate(VI) can be used to prepare ethanal by refluxing an excess of ethanol with an acidified solution of the oxidizing agent. The ethanal is distilled off as it is formed to prevent further oxidation to ethanoic acid. Primary alcohols are oxidized to aldehydes which can be further oxidized to carboxylic acids. Secondary alcohols

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
N a 2C r2O
7
/ H
H
+
H
C
H
O
C
H
N a 2C r2O
7
/ 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
H3C
C
CH3
H
N a 2C r2O
7
/ H
O
+
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