Given that addition of HBr to 1-phenylpropene yields only (1-bromopropyl) benzene. A mechanism for this reaction is to be proposed and why none of the other regioisomer is produced is to be explained. Concept introduction: The addition of HBr to alkenes takes place in two steps. In the first step the π electrons of the double bond picks up the positively polarized hydrogen of HBr to yield a more stable carbocation eliminating a bromide ion. In the next step the bromide ion attacks the carbocation from the less hindered side to yield the product. To propose: A mechanism for the reaction in which HBr adds to 1-phenylpropene to yield only (1-bromopropyl) benzene. To explain: Why none of the other regioisomer is produced.

Question

Treatment of a hydrocarbon A (molecular formula C9H18) with Br2 in the presence of light forms alkyl halides B and C, both having molecular formula C9H17Br. Reaction of either B or C with KOC(CH3)3 forms compound D (C9H16) as the major product. Ozonolysis of D forms cyclohexanone and acetone. Identify the structures of A–D.

Answer 1

Question

Chapter 16.SE, Problem 36MP

Interpretation Introduction

Interpretation:

Given that addition of HBr to 1-phenylpropene yields only (1-bromopropyl) benzene. A mechanism for this reaction is to be proposed and why none of the other regioisomer is produced is to be explained.

Concept introduction:

The addition of HBr to alkenes takes place in two steps. In the first step the π electrons of the double bond picks up the positively polarized hydrogen of HBr to yield a more stable carbocation eliminating a bromide ion. In the next step the bromide ion attacks the carbocation from the less hindered side to yield the product.

To propose:

A mechanism for the reaction in which HBr adds to 1-phenylpropene to yield only (1-bromopropyl) benzene.

To explain:

Why none of the other regioisomer is produced.

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