What does Markovnikov’s rule predict?
Markovnikov’s rule predicts the regiochemistry of the reaction when a protic acid (usually denoted by HX) is added to an unsymmetrically substituted alkene. It predicts that the halide part of the protic acid preferentially attaches itself to highly substituted carbon atoms whereas the hydrogen component of the protic acid preferentially attaches itself to the least substituted carbon atom (the carbon atom holding the most carbon-hydrogen bonds).
Which reactions do not obey Markovnikov’s rule?
Free radical addition reactions do not obey Markovnikov’s rule since the regioselectivity of the mechanisms of these reactions is not predicted by Markovnikov’s rule. These reactions are generally referred to as Anti-Markovnikov addition reactions.
What is markovnikov’s rule?
Markovnikov’s rule states that when an asymmetrical reagent is added to an asymmetrical alkene, then the negative half of the reagent will attach to the carbon atom containing fewer hydrogen atoms.
Name a reaction that follows markovnikov’s rule?
The addition of hydrogen halide to an unsymmetrical alkene follows markovnikov’s rule in the absence of hydrogen peroxide.
Why does Markovnikov’s rule work?
Markovnikov’s rule works on the basis of the formation of the most stable carbocation during the addition reaction. However, it does fail in the presence of peroxide and symmetrical alkenes.
What is the peroxide effect?
The modification in regioselectivity of the addition of HBr to an alkene or alkyne in the presence of peroxide is known as the peroxide effect. Under the presence of a peroxide, the negative half of the reagent will attach to the carbon atom containing more hydrogen atoms.
Name a compound that does not follow Markovnikov’s rule?
2-Butene does not follow Markovnikov’s rule as it is a symmetrical alkene.