Table of contents

1. A Review of General Chemistry5h 5m
2. Molecular Representations1h 14m
3. Acids and Bases2h 46m
4. Alkanes and Cycloalkanes4h 17m
5. Chirality3h 39m
6. Thermodynamics and Kinetics1h 22m
7. Substitution Reactions1h 48m
8. Elimination Reactions2h 30m
9. Alkenes and Alkynes2h 9m
10. Addition Reactions3h 19m
11. Radical Reactions1h 58m
12. Alcohols, Ethers, Epoxides and Thiols2h 42m
13. Alcohols and Carbonyl Compounds2h 17m
14. Synthetic Techniques1h 26m
15. Analytical Techniques:IR, NMR, Mass Spect7h 3m
16. Conjugated Systems6h 13m
17. Ultraviolet Spectroscopy51m
18. Aromaticity2h 34m
19. Reactions of Aromatics: EAS and Beyond5h 1m
20. Phenols55m
21. Aldehydes and Ketones: Nucleophilic Addition4h 56m
22. Carboxylic Acid Derivatives: NAS2h 51m
23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m
24. Enolate Chemistry: Reactions at the Alpha-Carbon1h 53m
25. Condensation Chemistry2h 9m
26. Amines1h 43m
27. Heterocycles2h 0m
28. Carbohydrates5h 53m
29. Amino Acids4h 20m
30. Peptides and Proteins2h 42m
31. Catalysis in Organic Reactions1h 30m
32. Lipids 2h 50m
33. The Organic Chemistry of Metabolic Pathways2h 52m
34. Nucleic Acids1h 32m
35. Transition Metals6h 14m
36. Synthetic Polymers1h 49m

22. Carboxylic Acid Derivatives: NAS

Saponification

Organic Chemistry

22. Carboxylic Acid Derivatives: NAS

Saponification

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4:45 minutes

Problem 22

Textbook Question

Propose a mechanism for the basic hydrolysis of benzonitrile to the benzoate ion and ammonia.

Verified step by step guidance

Identify the functional group in benzonitrile: The nitrile group (-C≡N) is a triple bond between carbon and nitrogen. In basic hydrolysis, this group is converted into a carboxylate ion (-COO⁻) and ammonia (NH₃).

Recognize the role of the base: The hydroxide ion (OH⁻) acts as a nucleophile and attacks the electrophilic carbon in the nitrile group, breaking the triple bond and forming an intermediate imidate ion.

Describe the intermediate hydrolysis step: The imidate ion undergoes further reaction with water, leading to the formation of an amide intermediate (benzamide). This step involves proton transfer and rearrangement.

Explain the second nucleophilic attack: The hydroxide ion attacks the carbonyl carbon of the amide, leading to the cleavage of the C-N bond and the formation of a tetrahedral intermediate.

Conclude with the final products: The tetrahedral intermediate collapses, releasing ammonia (NH₃) and forming the benzoate ion (C₆H₅COO⁻) as the final products of the reaction.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Nucleophilic Substitution

Nucleophilic substitution is a fundamental reaction mechanism in organic chemistry where a nucleophile attacks an electrophile, resulting in the replacement of a leaving group. In the case of benzonitrile hydrolysis, water acts as a nucleophile, attacking the carbon atom of the nitrile group, leading to the formation of an intermediate that eventually yields benzoate and ammonia.

Hydrolysis of Nitriles

Hydrolysis of nitriles involves the reaction of a nitrile with water, typically under basic or acidic conditions, to convert it into a carboxylic acid and ammonia. In this process, the nitrile carbon is converted to a carboxylate ion, while the nitrogen is released as ammonia, highlighting the transformation of functional groups during the reaction.

Reaction Mechanism

A reaction mechanism is a step-by-step description of the pathway taken during a chemical reaction, detailing the formation and breakdown of intermediates. Understanding the mechanism of benzonitrile hydrolysis is crucial, as it outlines the sequence of nucleophilic attack, intermediate formation, and final product generation, providing insight into the reaction's kinetics and thermodynamics.

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Related Practice

Textbook Question

Methyl p-nitrobenzoate has been found to undergo saponification faster than methyl benzoate.

(b) Would you expect methyl p-methoxybenzoate to undergo saponification faster or slower than methyl benzoate?

Textbook Question

What are the products of the following reactions?

Textbook Question

Propose a mechanism for the hydrolysis of N,N-dimethylacetamide

(a) under basic conditions.

Textbook Question

Propose a mechanism for the hydrolysis of N,N-dimethylacetamide

(b) under acidic conditions.

Multiple Choice

Which reaction conditions will turn olive oil into a soap?

Textbook Question

D. N. Kursanov, a Russian chemist, proved that the bond that is broken in the hydroxide-ion-promoted hydrolysis of an ester is the acyl C—O bond, rather than the alkyl C—O bond, by studying the hydrolysis of the following ester under basic conditions:

a. What products contained the ¹⁸O label?

b. What product would have contained the ¹⁸O label if the alkyl C—O bond had broken?

Textbook Question

The intermediate shown here is formed during the hydroxide-ion-promoted hydrolysis of the ester group. Propose a mechanism for the reaction.

Textbook Question

Predict the products and propose mechanisms for the following reactions.

(b)

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