Oxidation of Alcohols (WJEC GCSE Chemistry)

What is microbial oxidation?

• Microbial oxidation occurs when a substance is oxidised by microbes such as bacteria or yeast
• When ethanol undergoes oxidation ethanoic acid is formed
• The bacteria Acetobacter causes this reaction to take place
• We can use [O] in an equation to represent oxidation
  • Oxidation is also the removal of hydrogen from the ethanol, this is why water is formed
• The equation for this reaction is:

C₂H₅OH + 2[O] → CH₃COOH + H₂O

Ethanol being oxidised to ethanoic acid

We can use [O] to represent oxidation in an equation. When an alcohol is oxidised a carboxylic acid is formed.

• Whilst this process is useful in the manufacture of vinegar where ethanol (commonly sourced from fermented fruits or grains) is converted into ethanoic acid (vinegar) the process can lead to drink products being 'spoiled'
  • For example, beer and wine will 'go off' if left exposed to the air for a period of days
• This can also occur with other alcohols

Products from oxidation of alcohols

Alcohol	Oxidation product
Propanol	Propanoic acid
Butanol	Butanoic acid

Higher Tier

• Oxidation of the alcohol results in the carboxylic acid having a higher proportion of oxygen and a lower proportion of hydrogen than in the alcohol