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

8. Elimination Reactions

E2 Mechanism

Organic Chemistry

8. Elimination Reactions

E2 Mechanism

Previous problemNext problem

Problem 31

Textbook Question

Which compound has the greatest rate of hydrolysis at pH = 3.5: benzamide, o-carboxybenzamide, o-formylbenzamide, or o-hydroxybenzamide?

Verified step by step guidance

Identify the functional group in each compound. Benzamide contains an amide group (-CONH2). o-Carboxybenzamide has an amide group and a carboxylic acid group (-COOH) ortho to the amide. o-Formylbenzamide has an amide group and an aldehyde group (-CHO) ortho to the amide. o-Hydroxybenzamide has an amide group and a hydroxyl group (-OH) ortho to the amide.

Understand the mechanism of hydrolysis for amides. Amides hydrolyze in acidic conditions (pH = 3.5) through protonation of the carbonyl oxygen, making the carbonyl carbon more electrophilic and susceptible to nucleophilic attack by water.

Consider the electronic effects of the substituents ortho to the amide group. Electron-withdrawing groups (e.g., -COOH, -CHO) increase the electrophilicity of the carbonyl carbon by withdrawing electron density, thereby accelerating hydrolysis. Electron-donating groups (e.g., -OH) decrease the electrophilicity of the carbonyl carbon, slowing hydrolysis.

Compare the substituents in the given compounds. o-Carboxybenzamide and o-Formylbenzamide have electron-withdrawing groups (-COOH and -CHO, respectively), which enhance the rate of hydrolysis. o-Hydroxybenzamide has an electron-donating group (-OH), which reduces the rate of hydrolysis. Benzamide has no additional substituents, so its hydrolysis rate is unaffected by substituent effects.

Rank the compounds based on their expected hydrolysis rates. The compound with the strongest electron-withdrawing group ortho to the amide group will have the greatest rate of hydrolysis. Compare the effects of -COOH and -CHO to determine which compound hydrolyzes fastest.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Play a video:

Was this helpful?

Key Concepts

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

Hydrolysis

Hydrolysis is a chemical reaction involving the breakdown of a compound due to reaction with water. In organic chemistry, hydrolysis often refers to the cleavage of bonds in molecules, such as amides or esters, in the presence of water, leading to the formation of acids and alcohols or amines. The rate of hydrolysis can be influenced by factors such as pH, temperature, and the structure of the compound.

pH and its Effect on Hydrolysis

pH is a measure of the acidity or basicity of a solution, which can significantly affect the rate of hydrolysis reactions. At lower pH values, such as pH 3.5, the presence of protons (H+) can enhance the hydrolysis of certain compounds, particularly those that can stabilize a positive charge or form a more reactive intermediate. Understanding how pH influences the reactivity of functional groups is crucial for predicting hydrolysis rates.

Substituent Effects on Reactivity

The presence of different substituents on a benzene ring can greatly influence the reactivity of compounds in hydrolysis reactions. Electron-withdrawing groups, such as carboxylic acids or hydroxyl groups, can stabilize the transition state or intermediate, thereby increasing the rate of hydrolysis. Conversely, electron-donating groups may decrease reactivity. Analyzing the substituents on the given compounds helps determine which will hydrolyze fastest under acidic conditions.

Watch next

Master Drawing the E2 Mechanism. with a bite sized video explanation from Johnny

Start learning