Vladimir Markovnikov on his Rule
Me: Vladimir Markovnikov how are you?
VM: I am fine, thank you for asking. I understand your class is learning about HX adding to alkenes. Way back in 1870 I guessed that in these reactions with unsymmetrical alkenes, the H of the H-X will end up on the less-substituted carbon of the alkene and the X of the H-X will end up on the more-substituted carbon of the alkene. In other words, H adds to the carbon with more H atoms, so the X adds to the carbon with fewer H atoms. When I proposed this, I had absolutely no idea why it was true. Heck, back then, we did not even know what a covalent bond was! It was not until 1933 that Morris Kharasch figured it all out and especially why I was right. He explained that the reaction gives mostly the product derived from the more stable carbocation, the same product as my rule predicts. Hey, even if I did not know why… I WAS right. Besides, I think “Markovnikov’s rule” sounds better than “Kharasch’s rule”. Don’t you?
Me: Actually, no, I like either, but I see why you like Markovnikov's Rule.
VM: Exactly. Remember, Markovnikov’s rule predicts the regiochemistry of reactions of alkenes, in other words, which constitutional isomer of the product is formed in the greatest amount. The key is remembering that the more stable carbocation will lead to the predominant product, and the more stable carbocation is the more substituted one. Peace out from here.
