Using the principles for writing mechanisms and the four steps in the "How to Write Mechanisms for Interconversions of Carboxylic Acid Derivatives"box of this chapter, write mechanisms showing all electron flow arrows for the following reactions: (a) Hydrolysis of \(N, N\)-dimethylacetamide in acidic water. (b) Hydrolysis of acetic anhydride in basic water. (c) Esterification of acetic acid in acidic ethanol. (d) The reaction of dimethylamine in water with acetic anhydride to create N,N-dimethylacetamide. (e) Partial hydrolysis of acetonitrile in acidic water to create acetamide.

Short Answer

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2. What is the role of hydroxide ions in the hydrolysis of acetic anhydride in basic water? 3. What are the final products of the esterification of acetic acid in acidic ethanol? 4. What are the final products of the reaction of dimethylamine in water with acetic anhydride to create N, N-dimethylacetamide? 5. What is the final product of the partial hydrolysis of acetonitrile in acidic water?

Step by step solution

01

a) Hydrolysis of N, N-dimethylacetamide in acidic water

: 1. Protonation of the carbonyl group: In the presence of acidic water, the carbonyl oxygen of N, N-dimethylacetamide gets protonated, making it more electrophilic. 2. Nucleophilic attack by water: A water molecule acts as a nucleophile and attacks the electrophilic carbonyl carbon, forming a tetrahedral intermediate. 3. Deprotonation of the intermediate: The newly-added water molecule gets deprotonated, leading to the formation of an alcohol and amine with positive charge. 4. Deprotonation of the amine: The positively charged amine gets deprotonated, creating N, N-dimethylamine and acetic acid as the final products.
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b) Hydrolysis of acetic anhydride in basic water

: 1. Nucleophilic attack by hydroxide ion: In basic water, hydroxide ions act as nucleophiles and attack the electrophilic carbonyl carbon of acetic anhydride, forming a tetrahedral intermediate. 2. Collapse of the tetrahedral intermediate: The tetrahedral intermediate collapses, reforming the carbonyl group and transferring the acetate group to the hydroxide ion. 3. Formation of acetic acid and acetate ion: The acetate group combines with a proton to form acetic acid, while the hydroxide ion forms an acetate ion. The final products are acetic acid and acetate ion.
03

c) Esterification of acetic acid in acidic ethanol

: 1. Protonation of the carbonyl group: The presence of acidic ethanol causes the carbonyl oxygen of acetic acid to become protonated, making it more electrophilic. 2. Nucleophilic attack by ethanol: Ethanol acts as a nucleophile and attacks the electrophilic carbonyl carbon, forming a tetrahedral intermediate. 3. Deprotonation of the intermediate: The newly-added ethanol molecule gets deprotonated, leading to the formation of an ester and water. 4. Formation of the final product: The ester and water are the final products of the esterification reaction.
04

d) Reaction of dimethylamine in water with acetic anhydride to create N, N-dimethylacetamide

: 1. Nucleophilic attack by dimethylamine: Dimethylamine acts as a nucleophile and attacks the electrophilic carbonyl carbon of acetic anhydride, forming a tetrahedral intermediate. 2. Collapse of the tetrahedral intermediate: The tetrahedral intermediate collapses, reforming the carbonyl group and transferring the acetate group to dimethylamine. 3. Formation of N, N-dimethylacetamide and acetic acid: The acetate group combines with a proton from water to form acetic acid, while the carbonyl group becomes part of N, N-dimethylacetamide. The final products are N, N-dimethylacetamide and acetic acid.
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e) Partial hydrolysis of acetonitrile in acidic water to create acetamide

: 1. Protonation of the triple bond: In the presence of acidic water, the nitrogen in the nitrile group of acetonitrile gets protonated, making it more electrophilic. 2. Nucleophilic attack by water: A water molecule acts as a nucleophile and attacks the electrophilic carbon of the triple bond, forming an imine intermediate. 3. Hydrolysis of the imine: The imine undergoes hydrolysis in the presence of acidic water, leading to the formation of an oxygen on the carbon and a protonated nitrogen. 4. Deprotonation of the nitrogen: The protonated nitrogen of the intermediate gets deprotonated, forming acetamide as the final product.

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