Chapter 25, Problem 25.50P

Interpretation Introduction

(a)

Interpretation:

How to produce a given compound from a hydrocarbon that has the formula indicated is to be shown.

Concept introduction:

A hydrogen halide adds across the double bond of an alkene in a Markovnikov fashion under normal conditions. If a small amount of peroxide ($\text{RO-OR}$) is present, then $\text{HBr}$ still adds across the $\text{C=C}$ double bond, but with regiochemistry opposite to Markovnikov fashion. The $\text{H}$ atom adds to the more substituted $\text{C}$, and the $\text{Br}$ atom adds to the less substituted one. This is an anti-Markovnikov addition. Peroxides are radical initiators because they contain a weak $\text{O-O}$ bond. A free radical chain reaction involves free radicals in a cyclic sequence of steps, called propagation steps, which are responsible for converting overall reactants into overall products. Throughout the sequence of propagation steps, also called the propagation cycle, there is no net consumption of free radicals. The overall reaction is obtained by summing just the propagation steps. An initiation step is responsible for producing the free radical that enters the propagation cycle. A termination step removes free radicals from the propagation cycle and is responsible for slowing the overall reaction.

Interpretation Introduction

(b)

Interpretation:

How to produce given compound from a hydrocarbon that has the formula indicated is to be shown.

Concept introduction:

A hydrogen halide adds across the double bond of an alkene in a Markovnikov fashion under normal conditions. If a small amount of peroxide ($\text{RO-OR}$) is present, then $\text{HBr}$ still adds across the $\text{C=C}$ double bond, but with a regiochemistry opposite to Markovnikov fashion. The $\text{H}$ atom adds to the more substituted $\text{C}$, and the $\text{Br}$ atom adds to the less substituted one. This is an an anti-Markovnikov addition. Peroxides are radical initiators because they contain a weak $\text{O-O}$ bond. A free radical chain reaction involves free radicals in a cyclic sequence of steps, called propagation steps, which are responsible for converting overall reactants into overall products. Throughout the sequence of propagation steps, also called the propagation cycle, there is no net consumption of free radicals. The overall reaction is obtained by summing just the propagation steps. An initiation step is responsible for producing the free radical that enters the propagation cycle. A termination step removes free radicals from the propagation cycle and is responsible for slowing the overall reaction.