Chapter 22, Problem 22.91AP

Interpretation Introduction

(a)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

Bronsted-Lowry bases are those species which accept proton. They are also known as proton acceptors. Base accepts a proton and forms conjugate acid. The compound $\text{NaOEt}$ acts as a strong base to form carbanion in the chemical reaction.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 1

The reaction of given ester with $\text{NaOEt}$ forms carbanion which further reacts with ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$ followed by rearrangement to give the desired product. The complete mechanism is shown below.

Figure 2

Conclusion

The curved arrow mechanism is shown in Figure 2.

Interpretation Introduction

(b)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

Bronsted-Lowry bases are those species which accept proton. They are also known as proton acceptors. Base accepts a proton and forms conjugate acid. The compound $\text{NaOEt}$ acts as a strong base to form carbanion in the chemical reaction.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 3

The reaction of a given ester with substituted cyclic ether in the presence of a stong base undergoes ring closure with the help of internal nucleophile to form the desired product.

The complete mechanism is shown below.

Figure 4

Conclusion

The curved arrow mechanism is shown in Figure 4.

Interpretation Introduction

(c)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

The addition of proton in the chemical reaction is known as protonation. Water acts as a nucleophile due to the presence of lone pair on oxygen atom. Bronsted-Lowry bases are those species which accept proton. They are also known as proton acceptors. Base accepts a proton and forms conjugate acid.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 5

The reaction of given substrate with hydronium ion undergoes electrophilic addition followed by the addition of water molecule to form the desired product.

Figure 6

Conclusion

The curved arrow mechanism is shown in Figure 6.

Interpretation Introduction

(d)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

The addition of proton in the chemical reaction is known as protonation. Water acts as a nucleophile due to the presence of lone pair on oxygen atom. Bronsted-Lowry bases are those species which accept proton. They are also known as proton acceptors. Base accepts a proton and forms conjugate acid.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 7

The reaction of given substrate with ${\text{H}}^{\text{+}}$ undergoes protonation followed by the removal of phenol group to form the desired product.

Figure 8

Conclusion

The curved arrow mechanism is shown in Figure 8.

Interpretation Introduction

(e)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

Nucleophilic substitution reaction is the reaction in which a nucleophile attacks the electrophilic center and a substituted product is formed. It takes place by the generation of an electrophilic intermediate.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 9

The reaction of given substrate with $\text{KOH}$ in the presence of alcohol undergoes nucleophilic addition followed by heating with the removal of water gives keto-enol form in which keto form is the desired product. The complete reaction is shown below.

Figure 10

Conclusion

The curved arrow mechanism is shown in Figure 10.

Interpretation Introduction

(f)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

Nucleophilic substitution reaction is the reaction in which a nucleophile attacks the electrophilic center and a substituted product is formed. It takes place by the generation of an electrophilic intermediate.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 11

The reaction of given ester with substituted hydroxylamine undergoes nucleophilic substitution reaction followed by ring closure with the help of lone pair present on the nitrogen atom to form the desired product. The complete mechanism is shown below.

Figure 12

Conclusion

The curved arrow mechanism is shown in Figure 12.

Interpretation Introduction

(g)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

Ester undergoes hydrolysis in presence of base in aqueous solution. The ester upon hydrolysis forms the carboxylate salt and alcohol. The presence of alkene group with alcohol is known as enol form, which can undergo tautomerism to form the keto form of the compound.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 13

The reaction of given ester with substituted aldehyde in the presence of $\text{KCN}$ undergoes nucleophilic addition followed by hydrolysis in the presence of heat for the removal of carbon dioxide gas to form the desired product.

Figure 14

Conclusion

The curved arrow mechanism is shown in Figure 14.

Interpretation Introduction

(h)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

Nucleophilic substitution reaction is the reaction in which a nucleophile attacks the electrophilic center and a substituted product is formed. It takes place by the generation of an electrophilic intermediate.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 15

The reaction of given ester with cyanide ion undergoes nucleophilic addition followed by hydrolysis with the removal of carbon dioxide gas to form the desired product. The complete mechanism is shown below.

Figure 16

Conclusion

The curved arrow mechanism is shown in Figure 16.

Interpretation Introduction

(i)

Interpretation:

The curved arrow mechanism for the given reaction is to be predicted.

Concept introduction:

In the Wittig reaction, an aldehydes or a ketone reacts with triphenyl phophonium ylide to generate an alkene and triphenylphosphine oxide.

The triphenyl phophonium ylide is termed as Wittig reagent.

Answer to Problem 22.91AP

The curved arrow mechanism is shown below.

Explanation of Solution

The reaction to be completed is shown below.

Figure 17

The reaction of given substrate with triphenyl phophine to form ylide which further reacts with carbonyl compound undergoes nucleophilic addition followed by hydrolysis gives the desired product. The complete reaction is shown below.

Figure 18

Conclusion

The curved arrow mechanism is shown in Figure 18.