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I was reading about side chain oxidation of alkyl side chains of benzene using alkaline $\ce{KMnO4}$ and heat. My book (Solomon's and Frhyle) says that this is only for compounds having a benzylic hydrogen and has given examples of ethyl and methyl benzene. I have searched the internet but could not find a mechanism. I tried to find something of my use in that research paper given in this link.

I want to know what would happen if I take something like an ester or aldehyde/keto group, or any other organic functional group attached to a benzene ring. Will this reaction always happen with any aryl compound? Also, I came across an example of acetophenone being oxidized to benzoic acid by this method. It doesn't have a benzylic hydrogen so why does it still get oxidized?

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  • $\begingroup$ All the alkylated benzenes will oxidize to benzoic acid. It will always happen with any aryl molecule, in the case of poly alkylation you are able to make interesting compounds like phthalic acid, terephthalic acid (used in the PET plastic industry), isophthalic acid and much, much more. The answer is that this is right, acetophenone oxidize to benzoic acid if you are using the permanganate anion. $\endgroup$ – Java-Shake Jul 8 '15 at 16:26
  • $\begingroup$ This doesn't answer the question, it just restates the fact that acetophenone is oxidized to benzoic acid. The question is about why this occurs and the extent to which it occurs with other compounds. $\endgroup$ – bon Jul 8 '15 at 16:49
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    $\begingroup$ Also, all alkylated benzenes do not oxidize, for example, t-butyl benzene is inert to $\ce{KMnO4}$ $\endgroup$ – ron Jul 8 '15 at 16:54
  • $\begingroup$ I would suggest looking up oxidation of toluene by potassium dichromate in March. The mechanism is a radical one and I wouldn't be surprised if it's similar. $\endgroup$ – Beerhunter Jul 10 '15 at 23:13