Oxidation of Alcohols using Acidified Dichromate
Purpose:
To observe the oxidation of alcohols by acidified potassium dichromate.
To identify the type of alcohol based on their reaction with acidified dichromate.
Theory:
Primary and secondary alcohols can be oxidized by a strong oxidizing agent such as dichromate (VI)
ions. The reaction rate is increased by the presence of concentrated sulfuric acid.
Primary alcohols have two hydrogen atoms bound to the carbon that is bound to the hydroxyl (OH)
group. Primary alcohols are oxidized to form aldehydes. These aldehyde may themselves be
further oxidized to form carboxylic acids.
R-CH2OH +
1° alcohol
Cr2O72-+
[O]
dichromate (VI) oxygen

R – CHO
aldehyde
R- CHO +
aldehyde
Cr2O72-+
[O]
dichromate (VI) oxygen

R – COOH
carboxylic acid
Aldehydes are considered reaction intermediates when they are produced in one step of the reaction
and then consumed in a subsequent reaction step.
Secondary alcohols are oxidixed to form ketones.
Tertiary alcohols cannot be oxidized.
Materials:
potassium dichromate (0.1 M)
concentrated sulfuric acid (18 M)
various alcohols (specify)
test tubes
pipettes
Results:
Observations and determined type for various alcohols when mixed with acidified (0.1 M) potassium dichromate solution.
Alcohol Name
Structure
Observations
Alcohol Type (1° , 2° , 3° )
Observed
Expected