markownikoff's rule

Saoist

looked in books/googled for info about this...i know what it IS, but don't understand why it happens. anyone?

movies

Originally it was based on empirical evidence (it was just the product that you got from certain reactions) and was used as a predictive tool. It can be rationilized by thinking about the intermediates of a reaction mechanism. If a carbocation is formed then it will be more stable at the more substituted carbon and therefore a nucleophile would be more likely to attack at that position.

net_nubie

Well, I ain't sure of this but consider a 1-Methyl-2-butene. When HCl adds across the double bond, Cl radical will attract the electrons of the C=C towards itself creating a partial +ve charge on the C atoms. This partial positive charge is handled better by a 3rd degree C atom than the 2nd degree C atom. Thus the -ve part of the addendum will go the the C with more substituents, which is the Markonikov's rule.