How to convert propanoic acid to acetic acid

Both propanoic acid and acetic acid (ethanoic acid) are carboxylic acid compounds. Propanoic acid and acetic acid have three and two carbon atoms respectively. Therefore we have to reduce number of carbon atoms of propanoic acid by one when preparing acetic acid.


Follow below steps to prepare acetic acid from propanoic acid.

  1. Add LiAlH4 / ether to propanoic acid. It will give propanol (CH3CH2CH2OH) as the product. Propanol is a primary alcohol
  2. Next add concentrated sulfuric acid (H2SO4) to propanol and heat the mixture. Then, propanol is dehydrated (removal of water molecules) and propene (CH3CH=CH2) is given.
  3. Now, send Br2 / CCl4 into propene. Propene reacts with Br2 (an alkene) to and will give CH3CHBrCH2Br (alkyl halide).
  4. CH3CHBrCH2Br. is heated with alcoholic KOH to prepare CH3CCH (alkyne).
  5. Finally add acidic potassium dichromate ( H+ / KMnO4 ) to CH3CCH. It results acetic acid and CO2 gas.

how to convert propanoic acid to acetic acid


Acidity of propanoic acid and acetic acid

Acetic acid is more acidic than propanoic acid.

Acetic acid forms acetate ion and propanoic acid form propanoate ion. Acetate ion is much stable than propanoate ion.



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