# What results from the reaction of pent-3-en-2-ol with hydrogen bromide?

I have seen the following reaction in my textbook:

This was quite easy to understand, though I wonder why 2-bromopent-3-ene is not a possible result:

Isn't this how $\ce{-OH^}$ groups and hydrogen halides interact? Any clarification would be appreciated.

It is very rare for a reaction to have no side products, and this reaction is certainly not exceptional in that regard. I'm actually a bit surprised your book chose this reaction to illustrate the regiochemistry of $\ce{HBr}$ addition to an alkene, as this would compete with the formation of an allylic cation, which are generally more stable than alkyl carbocations. Being more stable, these cations will form more quickly: