Markovnikov Addition Paths in Alkenes

Markovnikov addition in alkenes explains why one product often forms in greater amount during hydrohalogenation. When an unsymmetrical alkene reacts, two haloalkane constitutional isomers are possible. In most cases, hydrogen adds to the vinylic carbon with more hydrogens, and the halide part adds to the more substituted car...

If a set of reactants can yield multiple constitutional isomers, but the formation of one product is favored, the reaction is regioselective.

For instance, when an unsymmetrical alkene, such as 2-methylpropene, undergoes hydrobromination, two bromoalkane products seem to be possible.

Here, the difference in relative stabilities of th...