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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: baum0372 on February 27, 2011, 06:27:15 PM

Title: Oxidation of Acetophenone
Post by: baum0372 on February 27, 2011, 06:27:15 PM

Hey everyone,

I've been struggling with figuring out why acetophenone reacts with potassium permanganate.  I ran a TLC of acetophenone and dipped it into a permanganate stain and it showed up as a brown spot.  I am trying to find oxidizable groups in the molecule.  I don't think the ketone will react because it cannot be oxidized further without breaking c-c bonds.  Does the heat gun make the double bonds in benzene more reactive toward the oxidation?

Thanks!

Title: Re: Oxidation of Acetophenone
Post by: baum0372 on February 27, 2011, 06:49:09 PM

Might have answered my own question.  Does it convert to the enol tautomer and then get oxidized?  But in this case, how does it convert to the enol tautomer when I only see 1 spot on the TLC plate?

Title: Re: Oxidation of Acetophenone
Post by: MissPhosgene on February 27, 2011, 09:24:09 PM

It does enolize first according to Canadian Journal of Chemistry, 48,2414 (1970).

You are probably seeing one spot because you dipped it into the solution after running the plate up. I'm not sure of the reaction goes to completion on the TLC spot scale, but maybe you would see two if you dipped the plate into the permanganate solution and then ran it up.

Title: Re: Oxidation of Acetophenone
Post by: kreisler on March 01, 2011, 09:21:24 AM

the methyl group next to ketone is relatively acidic.  And the  permanganate solution  you used must be basic (which is commonly used in chem lab). As a result,  acetophenone will be tautomerized to its enol form, which can be easily oxidized.