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

13. Alcohols and Carbonyl Compounds

Reducing Agent

Organic Chemistry

13. Alcohols and Carbonyl Compounds

Reducing Agent

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4:50 minutes

Problem 52

Textbook Question

An ether extraction of nutmeg gives large quantities of trimyristin, a waxy crystalline solid of melting point 57°C. The IR spectrum of trimyristin shows a very strong absorption at 1733 cm^-1. Basic hydrolysis of trimyristin gives 1 equivalent of glycerol and 3 equivalents of myristic acid (tetradecanoic acid).
(a) Draw the structure of trimyristin.
(b) Predict the products formed when trimyristin is treated with lithium aluminum hydride, followed by aqueous hydrolysis of the aluminum salts.

Verified step by step guidance

Step 1: Understand the structure of trimyristin. Trimyristin is a triglyceride, meaning it consists of a glycerol backbone esterified with three myristic acid (tetradecanoic acid) molecules. To draw its structure, start with a glycerol molecule (a three-carbon chain with hydroxyl groups on each carbon) and replace each hydroxyl group with an ester group formed by myristic acid (CH₃(CH₂)₁₂COOH).

Step 2: Analyze the IR spectrum data. The strong absorption at 1733 cm⁻¹ indicates the presence of a carbonyl group (C=O), which is characteristic of ester functional groups in trimyristin. This confirms the ester linkage between glycerol and myristic acid.

Step 3: Predict the products of lithium aluminum hydride (LiAlH₄) reduction. LiAlH₄ is a strong reducing agent that reduces esters to alcohols. When trimyristin is treated with LiAlH₄, the ester bonds are cleaved, converting the three myristic acid esters into three molecules of myristyl alcohol (CH₃(CH₂)₁₂CH₂OH) and regenerating the glycerol backbone.

Step 4: Consider the aqueous hydrolysis step. After reduction, the aluminum salts formed during the reaction are hydrolyzed with water, leaving behind the alcohol products (glycerol and myristyl alcohol) in their pure forms.

Step 5: Summarize the reaction products. The final products of the reaction sequence are glycerol (unchanged from the reduction step) and three equivalents of myristyl alcohol, which are derived from the reduction of the ester groups in trimyristin.

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Key Concepts

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

Structure of Trimyristin

Trimyristin is a triglyceride composed of glycerol and three myristic acid (tetradecanoic acid) molecules. Understanding its structure involves recognizing the ester linkages formed between the glycerol backbone and the fatty acid chains. The molecular formula is C45H86O6, and its structure can be represented as a glycerol molecule with three myristate groups attached, which is crucial for predicting its reactivity in chemical reactions.

Infrared (IR) Spectroscopy

IR spectroscopy is a technique used to identify functional groups in organic compounds based on their characteristic absorption of infrared light. The strong absorption at 1733 cm-1 in the IR spectrum of trimyristin indicates the presence of a carbonyl (C=O) group, typical of esters. This knowledge is essential for understanding the molecular structure and confirming the presence of ester linkages in trimyristin.

Lithium Aluminum Hydride Reduction

Lithium aluminum hydride (LiAlH4) is a powerful reducing agent commonly used to reduce esters and other carbonyl-containing compounds to their corresponding alcohols. In the case of trimyristin, treatment with LiAlH4 will reduce the ester groups to alcohols, yielding glycerol and myristyl alcohol upon hydrolysis. Understanding this reduction process is key to predicting the products formed after the reaction.

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Related Practice

Textbook Question

Predict the major products of the following reactions.

(f)

Textbook Question

Show how you would accomplish the following syntheses. You may use whatever additional reagents you need.

(a)

Textbook Question

Sodium triacetoxyborohydride, NaBH(OAc)₃, is a mild reducing agent that reduces aldehydes much more quickly than ketones. It can be used to reduce aldehydes in the presence of ketones, such as in the following reaction:

(b) Propose a mechanism for the reduction of an aldehyde by sodium triacetoxyborohydride.

Textbook Question

Show how you would accomplish the following synthetic conversions. You may use any additional reagents and solvents you need.

(b)

Textbook Question

Show how you would accomplish the following synthetic transformations. You may use any necessary reagents.

(a) N-ethylbenzamide → benzylethylamine

(b) ethyl benzoate → N-ethylbenzamide

Textbook Question

The esters shown differ only by the alkoxy group.

(i) Predict the product(s) obtained when these react with DIBAl-H.

(ii) Based on your answer, in a sequence like this, would there ever be a need to convert from one ester to another?