Chapter 20, Problem 20.35P

Interpretation Introduction

(a)

Interpretation:

The product of the reaction between $\text{m-ethylbenzoyl chloride}$ and the given reactant is to be predicted. A complete, detailed mechanism is to be drawn if the reaction occurs.

Concept introduction:

Carboxylic acid derivatives undergo acyl group substitution reactions when treated with appropriate nucleophiles. The reaction occurs via nucleophilic addition-elimination involving a tetrahedral intermediate. It may also involve proton transfer step(s). The reaction occurs if the possible product is more stable than the reactant. If the two are of comparable stability, the reaction will occur reversibly. The order of increasing stability of acid derivatives is

$\text{acid chloride < acid anhydride < ester }\approx \text{ carboxylic acid < amide < carboxylate anion}$.

Answer to Problem 20.35P

The product of the given reaction is

The complete mechanism of the reaction is

Explanation of Solution

The given reactant is NaOH, followed by ${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$. The reactant is an acid chloride, which is the least stable of the carboxylic acid derivatives. Therefore, the reaction will occur. The hydroxide ion from NaOH will replace the chlorine in the acid chloride, producing the corresponding carboxylic acid.

Thus, the product of the reaction will be

The reaction will start with the nucleophilic addition of the hydroxide ion from NaOH, producing a tetrahedral intermediate.

In the second step, one lone pair from the negatively charged oxygen will move back to the carbon to reform the carbonyl group and force the chlorine atom to leave as a chloride ion. This step will produce the corresponding carboxylic acid, but under the strongly basic conditions, it will be irreversibly deprotonated to the carboxylate anion.

The addition of the acid (${\text{H}}_{\text{3}}{\text{O}}^{\text{+}}$) at the end of this reaction will convert the carboxylate back to the acid.

Thus, the complete mechanism can be drawn as

Conclusion

The product of the reaction and its mechanism are determined based on the relative stability of the product and the nucleophilic addition-elimination mechanism.

Interpretation Introduction

(b)

Interpretation:

The product of the reaction between $\text{m-ethylbenzoyl chloride}$ and the given reactant is to be predicted. A complete, detailed mechanism is to be drawn if the reaction occurs.

Concept introduction:

Carboxylic acid derivatives undergo acyl group substitution reactions when treated with appropriate nucleophiles. The reaction occurs via nucleophilic addition-elimination involving a tetrahedral intermediate. It may also involve proton transfer step(s). The reaction occurs if the possible product is more stable than the reactant. If the two are of comparable stability, the reaction will occur reversibly. The order of increasing stability of acid derivatives is

$\text{acid chloride < acid anhydride < ester }\approx \text{ carboxylic acid < amide < carboxylate anion}$.

Answer to Problem 20.35P

The product of the given reaction is

The complete mechanism of the reaction is

Explanation of Solution

The given reactant is ${\text{CH}}_{\text{3}}\text{NHLi}$, which acts as the nucleophile ${\text{CH}}_{\text{3}}{\text{HN}}^{-}\text{:}$. Nucleophilic addition-elimination of the incoming nucleophile will produce an amide, which is more stable than the reactant acid chloride. Therefore, the nucleophile will add to the carbonyl carbon to produce a tetrahedral intermediate in the first step.

One lone pair on the negatively charged oxygen will move back to the carbon to reform the carbnyl group and eliminate chloride to form the final product.

Thus, the product of the reaction will be

And the complete mechanism can be drawn as

Conclusion

The product of the reaction and its mechanism are determined based on the relative stability of the product and the nucleophilic addition-elimination mechanism.

Interpretation Introduction

(c)

Interpretation:

The product of the reaction between $\text{m-ethylbenzoyl chloride}$ and the given reactant is to be predicted. A complete, detailed mechanism is to be drawn if the reaction occurs.

Concept introduction:

Carboxylic acid derivatives undergo acyl group substitution reactions when treated with appropriate nucleophiles. The reaction occurs via nucleophilic addition-elimination involving a tetrahedral intermediate. It may also involve proton transfer step(s). The reaction occurs if the possible product is more stable than the reactant. If the two are of comparable stability, the reaction will occur reversibly. The order of increasing stability of acid derivatives is

$\text{acid chloride < acid anhydride < ester }\approx \text{ carboxylic acid < amide < carboxylate anion}$.

Answer to Problem 20.35P

The product of the given reaction is

The complete mechanism of the reaction is

Explanation of Solution

The given reactant is ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{OK}$, containing the nucleophile ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{O}}^{-}$. Nucleophilic addition-elimination will produce an ester, a derivative that is more stable than the reactant acid chloride.

Therefore, the product of the reaction will be

In the first step, the incoming nucleophile will add to the carbonyl carbon, producing a tetrahedral intermediate.

The lone pair on the negativey charged oxygen will move back toward the carbon to reform the carbonyl group and eliminate chloride to form the final product, an ester.

Thus, the complete mechanism can be drawn as

Conclusion

The product of the reaction and its mechanism are determined based on the relative stability of the product and the nucleophilic addition-elimination mechanism.

Interpretation Introduction

(d)

Interpretation:

The product of the reaction between $\text{m-ethylbenzoyl chloride}$ and the given reactant is to be predicted. A complete, detailed mechanism is to be drawn if the reaction occurs.

Concept introduction:

Carboxylic acid derivatives undergo acyl group substitution reactions when treated with appropriate nucleophiles. The reaction occurs via nucleophilic addition-elimination involving a tetrahedral intermediate. It may also involve proton transfer step(s). The reaction occurs if the possible product is more stable than the reactant. If the two are of comparable stability, the reaction will occur reversibly. The order of increasing stability of acid derivatives is

$\text{acid chloride < acid anhydride < ester }\approx \text{ carboxylic acid < amide < carboxylate anion}$.

Answer to Problem 20.35P

The product of the given reaction is

The complete mechanism of the reaction is

Explanation of Solution

The given reactant is ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{CO}}_{\text{2}}\text{K}$ contains the nucleophile ${\text{C}}_{\text{6}}{\text{H}}_{\text{5}}{\text{COO}}^{-}$. Nucleophilic addition-elimination will produce an acid anhydride, more stable than the reactant.

Therefore, the product of the reaction will be

In the first step, the nucleophile will add to the carbonyl carbon to produce a tetrahedral intermediate.

In the second step, one lone pair of the negatively charged oxygen will move back to the carbon to reform the carbonyl group and eliminate chloride to form the final product.

Thus, the complete mechanism can be drawn as

Conclusion

The product of the reaction and its mechanism are determined based on the relative stability of the product and the nucleophilic addition-elimination mechanism.

Interpretation Introduction

(e)

Interpretation:

The product of the reaction between $\text{m-ethylbenzoyl chloride}$ and the given reactant is to be predicted. A complete, detailed mechanism is to be drawn if the reaction occurs.

Concept introduction:

Carboxylic acid derivatives undergo acyl group substitution reactions when treated with appropriate nucleophiles. The reaction occurs via nucleophilic addition-elimination involving a tetrahedral intermediate. It may also involve proton transfer step(s). The reaction occurs if the possible product is more stable than the reactant. If the two are of comparable stability, the reaction will occur reversibly. The order of increasing stability of acid derivatives is

$\text{acid chloride < acid anhydride < ester }\approx \text{ carboxylic acid < amide < carboxylate anion}$.

Answer to Problem 20.35P

There will be no reaction.

Explanation of Solution

The given reactant is ${\text{CH}}_3\text{Cl}$. Since the substituent on carbon is the highly electronegative chlorine, it can be a source of an electrophilic carbon, not a nuclophile needed for the reaction.

Therefore, the reaction will not occur.

Conclusion

Nucleophilic addition-elimination cannot occur since the given reactant is not a source of a nucleophile.

Interpretation Introduction

(f)

Interpretation:

The product of the reaction between $\text{m-ethylbenzoyl chloride}$ and the given reactant is to be predicted. A complete, detailed mechanism is to be drawn if the reaction occurs.

Concept introduction:

Carboxylic acid derivatives undergo acyl group substitution reactions when treated with appropriate nucleophiles. The reaction occurs via nucleophilic addition-elimination involving a tetrahedral intermediate. It may also involve proton transfer step(s). The reaction occurs if the possible product is more stable than the reactant. If the two are of comparable stability, the reaction will occur reversibly. The order of increasing stability of acid derivatives is

$\text{acid chloride < acid anhydride < ester }\approx \text{ carboxylic acid < amide < carboxylate anion}$.

Answer to Problem 20.35P

The reaction will not occur.

Explanation of Solution

The given reactant is ${\text{CH}}_{\text{3}}{\text{COCH}}_{\text{3}}$, an ether. Ethers are weak nucleophiles and do not add to a carbonyl carbon. The potential product is also not a derivative, that is, more stable than an acid chloride.

Therefore, there will be no reaction.

Conclusion

Nucleophilic addition-elimination is not possible in this case as the nucleophile is weak and does not add to a carbonyl carbon.