Chapter 22, Problem 22.55AP

Interpretation Introduction

(a)

Interpretation:

The principal organic product expected when $\text{3-buten-2-one}$ reacts with $\text{HBr}$ is to be stated.

Concept introduction:

The $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds undergo a variety of addition reactions. The addition occurs either at the unsaturated part, at carbonyl group or at the position that involves both the parts. Such type of addition reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds that involves conjugated addition is known as Michael addition.

Answer to Problem 22.55AP

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{HBr}$ is shown below.

Explanation of Solution

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{HBr}$ is shown below.

Figure 1

In this reaction, the addition of $\text{HBr}$ occurs only on the carbon-carbon double bond. This reaction is a simple addition to the double bond. The addition product here does not follow the Markonikov’s rule. In the product, hydrogen will add to that carbon of the double bond that has the least number of hydrogens.

Conclusion

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{HBr}$ is shown in Figure 1.

Interpretation Introduction

(b)

Interpretation:

The principal organic product expected when $\text{3-buten-2-one}$ reacts with ${\text{H}}_{\text{2}}\text{,}\text{Pt(cat}\text{.)}$ is to be stated.

Concept introduction:

The $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds undergo a variety of addition reactions. The addition occurs either at the unsaturated part, at carbonyl group or at the position that involves both the parts. Such type of addition reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds that involves conjugated addition is known as Michael addition.

Answer to Problem 22.55AP

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{H}}_{\text{2}}\text{,}\text{Pt(cat}\text{.)}$ is shown below.

Explanation of Solution

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{H}}_{\text{2}}\text{,}\text{Pt(cat}\text{.)}$ is shown below.

Figure 2

In this reaction, the addition of ${\text{H}}_{\text{2}}$ occurs only on the carbon-carbon double bond. This reaction is a simple addition to the double bond. This reaction is the selective reduction of the double bond in the presence of the carbonyl group.

Conclusion

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{H}}_{\text{2}}\text{,}\text{Pt(cat}\text{.)}$ is shown in Figure 2.

Interpretation Introduction

(c)

Interpretation:

The principal organic product expected when $\text{3-buten-2-one}$ reacts with ${\text{LiAlH}}_{\text{4}}$, then ${\text{H}}_{\text{2}}\text{O}$ is to be stated.

Concept introduction:

The $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds undergo a variety of addition reactions. The addition occurs either at the unsaturated part, at carbonyl group or at the position that involves both the parts. Such type of addition reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds that involves conjugated addition is known as Michael addition.

Answer to Problem 22.55AP

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{LiAlH}}_{\text{4}}$, then ${\text{H}}_{\text{2}}\text{O}$ is shown below.

Explanation of Solution

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{LiAlH}}_{\text{4}}$, then ${\text{H}}_{\text{2}}\text{O}$ is shown below.

Figure 3

In this reaction, the addition of ${\text{H}}_{\text{2}}$ occurs only on the carbonyl group. This reaction is the selective reduction of the carbonyl group in the presence of the double bond. The reduction of carbonyl groups leads to the formation of a secondary alcohol.

Conclusion

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{LiAlH}}_{\text{4}}$, then ${\text{H}}_{\text{2}}\text{O}$ is shown in Figure 3.

Interpretation Introduction

(d)

Interpretation:

The principal organic product expected when $\text{3-buten-2-one}$ reacts with $\text{HCN}$ in water, $\text{pH}10$ is to be stated.

Concept introduction:

The $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds undergo a variety of addition reactions. The addition occurs either at the unsaturated part, at carbonyl group or at the position that involves both the parts. Such type of addition reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds that involves conjugated addition is known as Michael addition.

Answer to Problem 22.55AP

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{HCN}$ in water, $\text{pH}10$ is shown below.

Explanation of Solution

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{HCN}$ in water, $\text{pH}10$ is shown below.

Figure 4

In this reaction, the addition of $\text{HCN}$ occurs only on the carbon-carbon double bond. The addition product here does not follow the Markonikov’s rule.

In the product, hydrogen will add to that carbon of the double bond that has the least number of hydrogens.

Conclusion

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{HCN}$ in water, $\text{pH}10$ is shown in Figure 4.

Interpretation Introduction

(e)

Interpretation:

The principal organic product expected when $\text{3-buten-2-one}$ reacts with ${\text{Et}}_{\text{2}}\text{CuLi}$, then ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is to be stated.

Concept introduction:

The $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds undergo a variety of addition reactions. The addition occurs either at the unsaturated part, at carbonyl group or at the position that involves both the parts. Such type of addition reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds that involves conjugated addition is known as Michael addition.

Answer to Problem 22.55AP

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{Et}}_{\text{2}}\text{CuLi}$, then ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is shown below.

Explanation of Solution

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{Et}}_{\text{2}}\text{CuLi}$, then ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is shown below.

Figure 5

The reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds with ${\text{R}}_{\text{2}}\text{CuLi}$ leads to the conjugate addition of alkane molecule on the double bond. In the first step of the reaction, ethyl anion attack on the double-bonded carbons and leads to the formation of enolate ions. The enolate ion on acidic workup gives enol which on tautomerism gives ketone, $\text{hexan-2-one}$ as a product.

Conclusion

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ${\text{Et}}_{\text{2}}\text{CuLi}$, then ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is shown in Figure 5.

Interpretation Introduction

(f)

Interpretation:

The principal organic product expected when $\text{3-buten-2-one}$ reacts with diethyl malonate and $\text{NaOEt}$, then ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is to be stated.

Concept introduction:

The $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds undergo a variety of addition reactions. The addition occurs either at the unsaturated part, at carbonyl group or at the position that involves both the parts. Such type of addition reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds that involves conjugated addition is known as Michael addition.

Answer to Problem 22.55AP

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with diethyl malonate and $\text{NaOEt}$, then ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is shown below.

Explanation of Solution

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with diethyl malonate and $\text{NaOEt}$, then ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is shown below.

Figure 6

The reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds with diethyl malonate leads to the conjugate addition of diethyl malonate molecule on the double bond. In the first step, acidic proton is abstracted by $\text{NaOEt}$ from diethyl malonate. This then attacks in a conjugated manner at the double bond. The final product is obtained after the hydrolysis.

Conclusion

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with diethyl malonate and $\text{NaOEt}$, then ${\text{H}}_{\text{3}}{\text{O}}^{+}$ is shown in Figure 6.

Interpretation Introduction

(g)

Interpretation:

The principal organic product expected when $\text{3-buten-2-one}$ reacts with ethylene glycol, $\text{HCl}\left(\text{cat}\text{.}\right)$ is to be stated.

Concept introduction:

The $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds undergo a variety of addition reactions. The addition occurs either at the unsaturated part, at carbonyl group or at the position that involves both the parts. Such type of addition reaction of $\alpha ,\beta \text{-}$ unsaturated carbonyl compounds that involves conjugated addition is known as Michael addition.

Answer to Problem 22.55AP

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ethylene glycol, $\text{HCl}\left(\text{cat}\text{.}\right)$ is shown below.

Explanation of Solution

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ethylene glycol, $\text{HCl}\left(\text{cat}\text{.}\right)$ is shown below.

Figure 7

The reaction of $\text{3-buten-2-one}$ with ethylene glycol leads to the addition of ethylene glycol molecule on the carbonyl group. This reaction is the protection of the carbonyl group so that reaction can be done on the rest of the molecule. The end product of the reaction is a ketal.

Conclusion

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with ethylene glycol, $\text{HCl}\left(\text{cat}\text{.}\right)$ is shown in Figure 7.

Interpretation Introduction

(h)

Interpretation:

The principal organic product expected when $\text{3-buten-2-one}$ reacts with $\text{1, 3-butadiene}$ is to be stated.

Concept introduction:

Diels-Alder reaction is a cycloaddition reaction. The reaction is known as a $\left[4+2\right]$ cycloaddition reaction in which a cis-diene and a dienophile react with each other in the presence of heat and a give a six-membered ring.

Answer to Problem 22.55AP

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{1, 3-butadiene}$ is shown below.

Explanation of Solution

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{1, 3-butadiene}$ is shown below.

Figure 8

The reaction of $\text{3-buten-2-one}$ with $\text{1, 3-butadiene}$ is diels-alder reaction. The $\left[4+2\right]$ cycloaddition of diene, $\text{1, 3-butadiene}$ and dienophile, $\text{3-buten-2-one}$ takes place. The double bond present in the $\text{3-buten-2-one}$ undergoes the addition reaction with $\text{1, 3-butadiene}$ to give six-membered ring product.

Conclusion

The principal organic product obtained when $\text{3-buten-2-one}$ reacts with $\text{1, 3-butadiene}$ is shown in Figure 8.