Why is a noncarbocation intermediate necessary for an antimarkovnikov halogenation to happen?
Anti-Markovnikov addition to a
When a carbocation intermediate forms, it usually seeks to stabilize itself through rearrangements: which are accomplished through methyl or hydride shifts.
Hence, it will generally become more substituted, and Markovnikov addition will take place, as a result.
When we have a radical initiator, like
If you want a detailed mechanism, ask!