Markovnikov’s Rule

Markovnikov’s Rule

what is it ?

While adding , an , unsymmetrical reagent such as HCl,Where H+  is  the electrophile,and Cl- is the nucleophile , to an unsymmetrical  double bond ,  

 the major product in each case is always the one where the electrophile (hydrogen) adds to the carbon in the double bond  with the most hydrogens, and the nucleophile(chlorine) adds to the carbon with the fewest hydrogens.

In other words, this reaction is REGIOSELECTIVE.  

you can see that in each case, we’re breaking C-C (π) and forming a new C-H and C-Cl bond. But ,

The major product in each case is always the one where the hydrogen adds to the carbon with the most hydrogens, and the chlorine adds to the carbon with the fewest hydrogens.

In other words, this reaction is  REGIOSELECTIVE

To describe this, the term “most substituted” is often thrown around a lot, so here is a graphical explanation:

REGIOSELECTIVE ???????? 

If more than one reaction could occur between a set of 

reactants under the same conditions giving products that

 are constitutional isomers  and if one product forms in greater 

amounts(MAJOR PRODUCT) than the others(MINOR 

PRODUCT), the overall reaction is said to be regioselective.

This empirical observation was first pointed out in 1870 by one Vladimir Markovnikov and this pattern of regioselectivity has become known as “Markovnikov’s rule”:

“when an unsymmetrical alkene reacts with a hydrogen halide to give an alkyl halide, the hydrogen adds to the carbon that has the greater number of hydrogen substituents, and the halogen to the carbon having the fewer number of hydrogen substituents”