Slide 1

Oxidation of
alcohols


Slide 2

Acidified potassium permanganate (H+/KMnO4), and
acidified potassium dichromate (H+/K2Cr2O7) are important
oxidising agents.

They will not react unless acid is present.
Purple H+/MnO4- turns colourless when it has reacted.
Orange H+/Cr2O72- turns blue/green when it has reacted.


Slide 3

Primary alcohol with
acidified dichromate;
secondary alcohol with
acidified permanganate,
tertiary alcohol with
acidified dichromate.

The reactions are very
slow unless heated in a
water bath.


Slide 4

The primary alcohol has
turned the dichromate
blue/green.
The secondary alcohol
has decolourised the
permanganate.

The tertiary alcohol has
not reacted with the
dichromate.


Slide 5

Primary alcohols are oxidised by acidified dichromate
or acidified permanganate. They form an aldehyde, and
then a carboxylic acid.
Secondary alcohols are also oxidised by these
oxidising agents. They form ketones.

Tertiary alcohols do not react with oxidising agents
such as permanganate and dichromate.