Chapter 11, Problem 11.56P

Interpretation Introduction

Interpretation:

The complete, detailed mechanism for the reaction of $\text{but-1-ene-3-yne}$ with HBr, producing $\text{4-bromobuta-1, 2-diene}$ is to be drawn.

Concept introduction:

The pi bond of an alkene or an alkyne is an electron-rich region. It undergoes electrophilic addition reaction when treated with a Bronsted acid. The addition of proton in the first step leads to the formation of a carbocation intermediate. The carbocation may undergo a rearrangement if it leads to a more stable carbocation. In the second step, the conjugate base of the acid adds to the carbocation.