I am interested in knowing how diols are produced when you introduce a reagent like potassium permanganate to an alkene. What is the mechanism for these reactions? The hydroxyl substituents happens to be at the 1,2 position each time.


That's a particular case of syn-dihydroxylation, also known as Wagner reaction. "Syn-dihydroxylation" means that a double bond is cleaved into a single bond and two OH groups are attached to the carbon atoms that were involved into a double bond from the same side. Anti-addition is not possible as permanganate anion can't be attached to the double bond from different sides of the bond due to steric reasons.
There is a Khan Academy video that describes the mechanism of this particular addition, but that video is all about different cases of syn-addition.
In brief, the mechanism can be also drawn as following: enter image description here


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.