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

21. Aldehydes and Ketones: Nucleophilic Addition

Acetal

Organic Chemistry

21. Aldehydes and Ketones: Nucleophilic Addition

Acetal

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3:52 minutes

Problem 37e

Textbook Question

Draw structures of the following derivatives.
(e) acetaldehyde dimethyl acetal

Verified step by step guidance

Understand the structure of acetaldehyde: Acetaldehyde is an aldehyde with the formula CH₃CHO. It contains a carbonyl group (C=O) attached to a methyl group (CH₃) and a hydrogen atom.

Recall the concept of an acetal: An acetal is formed when an aldehyde reacts with two equivalents of an alcohol in the presence of an acid catalyst. The carbonyl group (C=O) is replaced by two alkoxy groups (-OR).

Identify the alcohol used: In this case, the alcohol is methanol (CH₃OH), as the product is a dimethyl acetal. This means two methoxy groups (-OCH₃) will replace the carbonyl oxygen.

Draw the intermediate hemiacetal: The first step in the reaction involves the addition of one methanol molecule to the carbonyl group, forming a hemiacetal. The structure will have one -OCH₃ group and one -OH group attached to the central carbon.

Draw the final structure of acetaldehyde dimethyl acetal: Replace the -OH group in the hemiacetal with another -OCH₃ group, resulting in a central carbon atom bonded to two -OCH₃ groups, one CH₃ group, and one hydrogen atom. The final structure is CH₃-CH(OCH₃)₂.

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Key Concepts

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

Acetaldehyde

Acetaldehyde is a simple aldehyde with the chemical formula CH3CHO. It consists of a carbonyl group (C=O) attached to a methyl group (CH3) and a hydrogen atom. Understanding its structure is crucial for recognizing how it can react to form derivatives, such as acetals.

Acetal Formation

Acetals are formed when an aldehyde or ketone reacts with alcohol in the presence of an acid catalyst. This reaction involves the nucleophilic attack of the alcohol on the carbonyl carbon, leading to the formation of a hemiacetal, which can further react with another alcohol molecule to yield a full acetal. This process is essential for understanding how acetaldehyde dimethyl acetal is synthesized.

Dimethyl Acetal

Dimethyl acetal refers to a specific type of acetal where two methyl groups are attached to the oxygen atoms of the acetal functional group. In the case of acetaldehyde dimethyl acetal, the structure features two methoxy (–OCH3) groups replacing the hydrogen atom of the aldehyde. Recognizing this structure is key to drawing the correct molecular representation.

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