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Homework Help: Grignard reaction product involving a ketone

  1. Aug 1, 2011 #1
    1. The problem statement, all variables and given/known data

    Basically I have to show the product of this reaction:


    2. Relevant equations

    Grignard reaction mechanism:
    The conversion of a ketone to an alcohol

    3. The attempt at a solution

    My attempt of this reaction produces an alcohol with two ethyl groups attached to the central carbon as well as a phenyl group and an OH group attached to the central carbon, so the IUPAC name would be 3-phenyl-3-pentanol.

    However, the answer is:

    Can someone please explain why the reaction produced an alkene instead of an alcohol. I do not know why this occurred and need some clarification. Also, when does this extra step occur.

  2. jcsd
  3. Aug 1, 2011 #2
    Think a little about step 3.
  4. Aug 1, 2011 #3
    What occurs is step 3? I know that the H2SO4 is deprotonated to become HSO4. This produces the alcohol part of the compound, which is what I got. I am going to assume that deprotonation of HSO4 occurs, thus producing water and the alkene as shown in the answer. Is this right?
  5. Aug 1, 2011 #4
    Look up "dehydration". Sulfuric acid is a powerful dessicant.
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