Chapter 9.SE, Problem 29AP

Interpretation Introduction

Interpretation:

Given that terminal alkynes react with bromine and water to yield bromoketones. A mechanism for the reaction is to be proposed. To what reaction of alkenes this reaction is analogous is also to be stated.

Concept introduction:

Addition of bromine to alkynes occurs through the formation of a cyclic bromonium ion intermediate. Water being nucleophilic, if present will attack the bromonium ion to yield an enol. The enol will then tautomerize to a ketone. Thus in thr product a bromine and a hydroxyl group are added to the triple bond. This reaction is similar to the addition of halohydrins to alkenes.

To propose:

A mechanism for the reaction in which ethynylbenzene reacts with bromine and water to yield a bromoketone is to be proposed. Further to state to what reaction of alkenes this reaction resembles.