I was doing a high school lab, and according to my expectations for organic chemistry reactions, the following reaction of potassium permanganate and tert-butyl alcohol (t-butanol) should occur:

KMnO4 + C4H10O -> No Reaction

This is because, as far as I understand, while primary alcohols produce aldehydes and secondary alcohols produce ketones, tertiary alcohols do not react in standard oxidation.

My issue is that when I combined 3mL of t-butanol and 1mL of potassium permanganate, plus an H2SO4 (sulfuric acid) catalyst, a visible reaction did occur, turning the solution Orange.

For reference, the initial colour of t-butanol is clear, and KMnO4 is a clear but pink colour.

My initial thoughts are there must be some sort of contaminant. That being said, the only other chemicals nearby that COULD have possible contaminated the solution if someone mixed pipettes werea sec-butyl alcohol and 1-butanol, and I already know the reaction for those with potassium permanganate produces a clear product.

This is my first time using the chemistry StackExchange but I'm used to using StackOverflow, so please feel free to let me know if there is anything missing in my question and I will put it in an addendum in my post. All help appreciated.


Maybe it formed formaldehyde?


1 Answer 1


Normally, the tertiary alcohols do not react with potassium permanganate. However, you added a strong acid (H2SO4). So, the sulfuric acid can react with the alcohol, generating an alkene, and then the alkene could oxidize with potassium permanganate. enter image description here

  • 1
    $\begingroup$ I think I understand: The acid generated isobutylene, which in turn was oxidized by the potassium permanganate originally intended to prove that tert-butyl alcohol doesn't react. This is then oxidized into water, carbon dioxide, and 2-propanone (acetone). This makes sense. But my understanding of acetone is that it's clear (as is water and carbon dioxide obviously). What's the cause of the colour change? $\endgroup$
    – Isaac K
    Nov 14, 2021 at 22:19
  • $\begingroup$ It is probably $\ce{MnO2}$. $\endgroup$
    – M.L
    Nov 16, 2021 at 6:19
  • $\begingroup$ When I ran reactions with KMnO4, the reaction media became slightly yellow due to the MnO2... I agree with M.L. It could be the MnO2. Or it's other impurities, I guess. $\endgroup$
    – Koba
    Nov 16, 2021 at 9:25
  • 1
    $\begingroup$ Thank you! You were both right $\endgroup$
    – Isaac K
    Feb 5 at 20:47

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