4.2.2 Ethanol Oxidation

Oxidation of ethanol

• Primary alcohols can be oxidised to form aldehydes which can undergo further oxidation to form carboxylic acids
  • When ethanol is oxidised, ethanal is produced and when oxidised further ethanoic acid will be formed

Synthesis and purification of ethanal and ethanoic 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 ethanol 
• Using a pipette, slowly add the ethanol drop wise into the reflux condenser
• When the ethanol 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 
  • Ethanol 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 ethanol to ethanoic acid

Oxidation of ethanol by acidified K₂Cr₂O₇ to form an aldehyde by distillation