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

28. Carbohydrates

Monosaccharides - Alkylation

Organic Chemistry

28. Carbohydrates

Monosaccharides - Alkylation

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1:35 minutes

Problem 30b

Textbook Question

Predict the product of the following etherification reactions.
(b)

Verified step by step guidance

Identify the functional groups present in the starting material. The molecule is a sugar derivative with multiple hydroxyl (OH) groups and an allyl ether group.

Recognize the reagents used in the reaction. The reagent is trimethylsilyl chloride ((CH₃)₃SiCl) in excess, along with triethylamine (Et₃N) in excess.

Understand the role of the reagents. Trimethylsilyl chloride is used to protect hydroxyl groups by converting them into trimethylsilyl ethers, which are less reactive. Triethylamine acts as a base to facilitate the reaction.

Predict the reaction outcome. The excess of trimethylsilyl chloride will likely convert all the hydroxyl groups into trimethylsilyl ethers, protecting them from further reactions.

Consider the stereochemistry and regioselectivity. Since all hydroxyl groups are converted to silyl ethers, the stereochemistry of the sugar ring remains unchanged, and the allyl ether group is unaffected by the silylation process.

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Key Concepts

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

Etherification Reaction

Etherification is a chemical reaction that forms an ether from an alcohol and an alkylating agent. In this reaction, the hydroxyl groups (OH) of the alcohol are replaced by an alkoxy group (OR), typically using a reagent like an alkyl halide. Understanding the mechanism of etherification is crucial for predicting the product, as it involves the substitution of the hydroxyl group with an ether linkage.

Silyl Ether Protection

Silyl ether protection involves the conversion of hydroxyl groups into silyl ethers using reagents like chlorotrimethylsilane (TMSCl) in the presence of a base such as triethylamine (Et3N). This reaction is used to protect alcohols from unwanted reactions by forming a stable silyl ether, which can be removed later. In the given reaction, excess (CH3)3SiCl suggests the formation of silyl ethers, protecting the hydroxyl groups.

Role of Triethylamine

Triethylamine (Et3N) acts as a base in organic reactions, often used to neutralize acids formed during reactions or to facilitate the deprotonation of alcohols. In the context of silyl ether formation, Et3N helps in the deprotonation of the hydroxyl group, allowing the silyl chloride to react and form the silyl ether. Its presence in excess ensures complete conversion of all hydroxyl groups to silyl ethers.