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Homework Help: Jones Oxidation

  1. Jul 20, 2007 #1
    1. The problem statement, all variables and given/known data

    I am trying to figure out the complete reaction equation for the oxidation of a secondary alcohol, 2-butanol, with CrO3 (and H2SO4).



    2. Relevant equations

    See below.

    3. The attempt at a solution

    In this oxidation, the alcohol is turned into a ketone, not a carboxylic acid, correct?

    Therefore, the simple synthesis setup would be:

    CH3CH2CH(OH)CH3 + CrO3 + H2SO4 -> CH3CH2C(=O)CH3

    Now for the redox reaction with the chromium ions:

    (Please note that I am slightly rusty on balancing redox reactions, and I really don’t know if this is remotely valid.)

    CrO3 -> Cr(+3)
    CH3CH2CH(OH)CH3 -> CH3CH2C(=O)CH3 ??

    3 e- + CrO3 + 6 H(+) -> Cr(+3) + 3H2O
    CH3CH2CH(OH)CH3 -> CH3CH2C(=O)CH3 + H(+) + 1 e-

    3 e- + CrO3 + 6 H(+) -> Cr(+3) + 3H2O
    3*(CH3CH2CH(OH)CH3 -> CH3CH2C(=O)CH3 + H(+) + 1 e-)


    3 e- + CrO3 + 6 H(+) -> Cr(+3) + 3H2O
    3 CH3CH2CH(OH)CH3 -> 3 CH3CH2C(=O)CH3 + 3H(+) + 3 e-
    CrO3 + 6 H(+) + 3 CH3CH2CH(OH)CH3 -> Cr(+3) + 3H2O + 3 CH3CH2C(=O)CH3 + 3H(+)

    CrO3 + 3 H(+) + 3 CH3CH2CH(OH)CH3 -> Cr(+3) + 3H2O + 3 CH3CH2C(=O)CH3 ?

    Thank you.
     
  2. jcsd
  3. Jul 22, 2007 #2
    Yeah. Looks right.
     
  4. Jul 22, 2007 #3
    I just came across this equation for the oxidation in a book.

    2CrO3 + 6 H(+) + 3 CH3CH2CH(OH)CH3 -> 2Cr(+3) + 6H2O + 3 CH3CH2C(=O)CH3

    Why is it that the bold coefficients are two times more than those in my equation?

    Did I do something wrong?

    Thanks again.
     
    Last edited: Jul 22, 2007
  5. Jul 24, 2007 #4

    chemisttree

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    Rethink this... pay attention to the hydrogens I have bolded.
     
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