Chapter 23, Problem 23.13P

Interpretation Introduction

(a)

Interpretation: The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{Li}}_{\text{2}}{\text{O}}_{\text{3}}$, $\text{LiBr}$, DMF is to be drawn.

Concept introduction: The bimolecular elimination reaction that favours the removal of a HX substituent from an alkyl halide that needs a base to remove $\text{H}$ from carbon adjacent to the leaving group that in turn forms a double bond is termed ${\text{E}}^2$ elimination reaction.

Answer to Problem 23.13P

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{Li}}_{\text{2}}{\text{O}}_{\text{3}}$, $\text{LiBr}$, DMF is shown below.

Explanation of Solution

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{Li}}_{\text{2}}{\text{O}}_{\text{3}}$, $\text{LiBr}$, DMF is shown as,

Figure 1

In this reaction, the given ketone, $2-\text{bromopentan}-3-\text{one}$ is treated with ${\text{Li}}_{\text{2}}{\text{O}}_{\text{3}}$, $\text{LiBr}$, in the presence of DMF solution to form $\alpha ,\beta -\text{unsaturated}$ compound. The compound, $2-\text{bromopentan}-3-\text{one}$ undergoes elimination reaction with the base, ${\text{Li}}_{\text{2}}{\text{O}}_{\text{3}}$ in the presence of $\text{LiBr}$ and polar aprotic solvent DMF. In this reaction, $\text{HBr}$ gets eliminated.

Conclusion

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{Li}}_{\text{2}}{\text{O}}_{\text{3}}$, $\text{LiBr}$, DMF is shown in Figure 1.

Interpretation Introduction

(b)

Interpretation: The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$ is to be drawn.

Concept introduction: The substitution reaction involves the replacement of one functional group by other functional group. In nucleophilic substitution an electron rich species attack the species that is deficient in electrons. The electrophile and the leaving group together form a substrate. The nucleophile attacks over the substrate and there occurs the removal of leaving group from the substrate.

The nucleophilic reaction that consists of bimolecular as well as bond-making and bond-breaking steps is termed as ${\text{S}}_{\text{N}}\text{2}$ reactions. This is a one-step reaction in which both nucleophile and substrate participate in the rate determining step.

Answer to Problem 23.13P

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$ is shown below.

Explanation of Solution

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$ is shown as,

Figure 2

In this reaction, the given ketone, $2-\text{bromopentan}-3-\text{one}$ is treated with ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$ to form the desired product. The compound, $2-\text{bromopentan}-3-\text{one}$ undergoes ${\text{S}}_{\text{N}}\text{2}$, substitution reaction with the nucleophile, methanethiol.

Conclusion

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{NH}}_{\text{2}}$ is shown in Figure 2.

Interpretation Introduction

(c)

Interpretation: The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{CH}}_{\text{3}}\text{SH}$ is to be drawn.

Concept introduction: The substitution reaction involves the replacement of one functional group by other functional group. In nucleophilic substitution an electron rich species attack the species that is deficient in electrons. The electrophile and the leaving group together form a substrate. The nucleophile attacks over the substrate and there occurs the removal of leaving group from the substrate.

The nucleophilic reaction that consists of bimolecular as well as bond-making and bond-breaking steps is termed as ${\text{S}}_{\text{N}}\text{2}$ reactions. This is a one-step reaction in which both nucleophile and substrate participate in the rate determining step.

Answer to Problem 23.13P

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{CH}}_{\text{3}}\text{SH}$ is shown below.

Explanation of Solution

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{CH}}_{\text{3}}\text{SH}$ is shown as,

Figure 3

In this reaction, the given ketone, $2-\text{bromopentan}-3-\text{one}$ is treated with ${\text{CH}}_{\text{3}}\text{SH}$ to form the desired product. The compound, $2-\text{bromopentan}-3-\text{one}$ undergoes ${\text{S}}_{\text{N}}\text{2}$, substitution reaction with the nucleophile, methanethiol.

Conclusion

The product that is formed by the reaction of $2-\text{bromopentan}-3-\text{one}$ with ${\text{CH}}_{\text{3}}\text{SH}$ is shown in Figure 3.