What is the product of the permanganate oxidation of 1-methylindane (1-methyl-2,3-dihydro-1⁠H-indene)?


There are two choices of benzylic protons (one proton on the carbon with the methyl group at the top of the cyclopentane, and two protons on the carbon in the cyclopentane at the bottom of the molecule).

I figure that the ketone is added to the carbon that has two benzylic protons, and that the other carbon with a benzylic proton is untouched. Am I correct?


For the homogenous permanganate oxidation of aromatic side chains, as long as there is at least one benzylic hydrogen, then the side chain will be oxidized to the corresponding benzoic acid. Here are some examples.

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(image source)

Look at the third example, the permanganate oxidation of tetralin to phthalic acid. It is very analogous to your molecule. Your molecule would also be oxidized to phthalic acid.

  • $\begingroup$ @ron what's the mechanism of oxidative cleavage? $\endgroup$ – Dissenter Apr 6 '15 at 21:32
  • 2
    $\begingroup$ @Dissenter Some experiments, lots of theories, no one really knows. $\endgroup$ – ron Apr 6 '15 at 21:57
  • $\begingroup$ @ron, I think we need an example of isopropylbenzene oxidation to the acid... $\endgroup$ – Zhe Nov 23 '16 at 15:14
  • $\begingroup$ @Zhe the isopropyl case can be interpolated from the above data. $\endgroup$ – ron Dec 10 '16 at 15:34
  • $\begingroup$ I'm not sure that's true. You have no example of a secondary alkyl case. Based on the series you have, is the requirement that we have a benzylic hydrogen or do we need 2? $\endgroup$ – Zhe Dec 10 '16 at 18:20

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