Skip to main content
Chemistry LibreTexts

19.9: Reduction of Carboxylic Acids

  • Page ID
    183116
  • Carboxylic acids can be converted to 1o alcohols using Lithium aluminum hydride (LiAlH4)

    Note that NaBH4 is not strong enough to convert carboxylic acids or esters to alcohols. An aldehyde is produced as an intermediate during this reaction, but it cannot be isolated because it is more reactive than the original carboxylic acid.

    1.jpg

    For example, butanoic acid can be reduced to butanol when reacted with lithium aluminum hydride as shown below.

    ch 21 sect 9 example 1.png

    Possible Mechanism

    There is not complete agreement on the mechanism for this reaction.  However, the mechanism below is considered probable by many chemists.

    1) Deprotonation

    4.jpg

    2) Nucleopilic reaction by the hydride anion

    5.jpg

    3) Leaving group removal

    6.jpg

    4) Nucleopilic reaction by the hydride anion

    7.jpg

    5) The alkoxide is protonated

    8.jpg

    Exercise

    8. Using benzyl bromide and sodium cyanide as the only source of carbons, propose a synthetic strategy to produce 2-phenyl-ethan-1-ol.

    Answer

    8.

    ch 21 sect 9 exercise solution.png

    Contributors