Answer
In this reaction but-1-ene $-->$ 2-bromobutane. The reaction that it undergoes is addition of Hydrogen Halides to alkenes.
Work Step by Step
Draw the skeletal structures of the given compound names. In this one, it can be seen that the bromine is added to the most substituted carbon on the double bond. Thus, it can be concluded that the synthetic conversion that it went through is simple addition of HBr.
The electrons in the double bond attack on the H, forming a carbocation at the most substituted carbon. The Bromine ion comes and attacks on the carbocation and forms the product. In absence of peroxides, the halogen is always added to the most substituted carbon on the double bond.
