Propan-1-ol Oxidation (Edexcel International AS Chemistry)

Oxidation of propan-1-ol

• Primary alcohols can be oxidised to form aldehydes which can undergo further oxidation to form carboxylic acids
  • When propan-1-ol is oxidised, ethanal is produced and when oxidised further propanoic acid will be formed

Synthesis and purification of propanal and propanoic acid 

• Carefully add 20 cm³ of acidified potassium dichromate(VI) solution, K₂Cr₂O₇ (aq), to a 50 cm³ pear-shaped flask and cool the flask in an iced water bath
• Set up the reflux apparatus keeping pear shaped flask cool
• Place anti-bumping granules into the pear shaped flask 
• Measure out 1 cm³ of propan-1-ol 
• Using a pipette, slowly add the propan-1-ol drop wise into the reflux condenser
• When the propan-1-ol has been added remove the ice bath and allow to warm up to room temperature 
• Position the flask over an electric heater or in a water bath and heat for 20 minutes 
  • Propan-1-ol is flammable, therefore. naked flames should not be used when heating which is why the use of an electric heater or water bath is an important safety precaution 
• Purify the product using distillation apparatus 

Reflux apparatus for the oxidation of propan-1-ol to propanoic acid

Oxidation of propan-1-ol by acidified K₂Cr₂O₇ to form propanal by distillation

Hazards, risks and precautions

• The alcohols used are flammable and often harmful to health, e.g, propan‐1‐ol, butan‐1‐ol, pentan‐1‐ol
• The alcohols should be kept away from naked flames, e.g. a Bunsen burner
• Avoid contact with the skin and breathing in the vapour
• A fume cupboard can be used for harmful alcohols
• Potassium dichromate is a strong oxidising agent and should be handled with care
• Spillages should be mopped up right away with plenty of water