Biography of markovnikov regioselectivity

Alkene Addition Reactions: Regioselectivity and Stereoselectivity

• Almost all reactions of alkenes we will learn about can be classified as addition reactions 
• In an alkene addition reaction, a C-C pi bond breaks, and two new single bonds to carbon are formed
• Depending on the structure of the alkene and the bonds formed/broken in the reaction, a mixture of constitutional isomers may be formed.

  In alkene addition reactions, these are often called “regioisomers”.

• When formation of one regioisomer is favored this is called “regioselectivity“. The most common example of regioselectivity is “Markovnikov” selectivity observed in addition of H-X to alkenes, where the C-H bond forms on the “least substituted” carbon (fewest carbons directly attached) and the C-X bond forms on the “most substituted” car