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

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Acetoacetic Ester Synthesis

Organic Chemistry

24. Enolate Chemistry: Reactions at the Alpha-Carbon

Acetoacetic Ester Synthesis

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9:52 minutes

Problem 68

Textbook Question

The ketone whose ¹H NMR spectrum is shown here was obtained as the product of an acetoacetic ester synthesis. What alkyl halide was used in the synthesis?
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Verified step by step guidance

Step 1: Analyze the molecular formula provided in the image, C₅H₁₀O, which indicates the compound is a ketone with five carbons, ten hydrogens, and one oxygen atom.

Step 2: Examine the ¹H NMR spectrum. The spectrum shows three distinct signals: a singlet at approximately 2.1 ppm (3H), a quartet at approximately 2.4 ppm (2H), and a triplet at approximately 1.0 ppm (3H). These signals correspond to different proton environments in the molecule.

Step 3: Interpret the singlet at 2.1 ppm (3H). This signal is characteristic of a methyl group directly attached to a carbonyl group (CH₃-C=O), which is consistent with the ketone functional group.

Step 4: Analyze the quartet at 2.4 ppm (2H) and the triplet at 1.0 ppm (3H). These signals suggest the presence of an ethyl group (-CH₂-CH₃) attached to the molecule. The quartet corresponds to the CH₂ group adjacent to the carbonyl group, and the triplet corresponds to the CH₃ group further away.

Step 5: Based on the acetoacetic ester synthesis mechanism, the alkyl halide used must introduce the ethyl group into the molecule. Therefore, the alkyl halide used in the synthesis is ethyl bromide (CH₃CH₂Br).

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Key Concepts

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

Acetoacetic Ester Synthesis

Acetoacetic ester synthesis is a method for synthesizing ketones through the reaction of an acetoacetic ester with an alkyl halide. This process involves the formation of a β-keto ester, which can be hydrolyzed and decarboxylated to yield the desired ketone. Understanding this synthesis is crucial for identifying the starting materials and the resulting products in organic reactions.

NMR Spectroscopy

Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful analytical technique used to determine the structure of organic compounds. In 1H NMR, the chemical environment of hydrogen atoms is analyzed, providing information about the number of hydrogen atoms, their connectivity, and the presence of functional groups. Peaks in the spectrum correspond to different hydrogen environments, which are essential for deducing the structure of the synthesized ketone.

Alkyl Halides in Organic Synthesis

Alkyl halides are organic compounds containing a carbon atom bonded to a halogen atom (F, Cl, Br, I). They are commonly used as electrophiles in nucleophilic substitution reactions, making them key reagents in organic synthesis. Identifying the specific alkyl halide used in the acetoacetic ester synthesis is critical for understanding the reaction pathway and the final structure of the ketone produced.

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The ketone whose 1H NMR spectrum is shown here was obtained as the product of an acetoacetic ester synthesis. What alkyl halide was used in the synthesis?<IMAGE>

Key Concepts

Acetoacetic Ester Synthesis

NMR Spectroscopy

Alkyl Halides in Organic Synthesis

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The ketone whose ¹H NMR spectrum is shown here was obtained as the product of an acetoacetic ester synthesis. What alkyl halide was used in the synthesis?
<IMAGE>