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

26. Amines

Amines by Reduction

Organic Chemistry

26. Amines

Amines by Reduction

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2:58 minutes

Problem 50e,f

Textbook Question

Predict the products of the following reactions.
(e)
(f)

Verified step by step guidance

Step 1: Analyze the first reaction. The starting material is an ester (Ph-C(O)-OCH2CH3), and the reagents are lithium aluminum hydride (LiAlH4) followed by water (H2O). LiAlH4 is a strong reducing agent that reduces esters to primary alcohols. The ester bond will be cleaved, and the carbonyl group will be reduced to an alcohol.

Step 2: Predict the product for the first reaction. The phenyl group (Ph) remains attached to the carbon, and the ethoxy group (-OCH2CH3) is replaced by a hydroxyl group (-OH). This results in the formation of benzyl alcohol (Ph-CH2OH).

Step 3: Analyze the second reaction. The starting material is a lactam (cyclic amide), and the reagents are LiAlH4 followed by H2O. LiAlH4 reduces amides to amines by breaking the C=O bond and converting the carbonyl group into a CH2 group.

Step 4: Predict the product for the second reaction. The cyclic structure remains intact, but the carbonyl group is reduced to a CH2 group, resulting in a cyclic amine. The product is a six-membered ring with a secondary amine (-NH) and a CH2 group replacing the carbonyl.

Step 5: Summarize the reaction outcomes. For reaction (e), the ester is reduced to benzyl alcohol. For reaction (f), the lactam is reduced to a cyclic amine. Both reactions involve the use of LiAlH4 as a reducing agent followed by hydrolysis with water.

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Key Concepts

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

Reduction Reactions

Reduction reactions involve the gain of electrons or the decrease in oxidation state of a molecule. In organic chemistry, this often refers to the conversion of carbonyl compounds (like aldehydes and ketones) to alcohols. Lithium aluminum hydride (LiAlH4) is a strong reducing agent commonly used to reduce carbonyl groups, resulting in the formation of alcohols.

Lithium Aluminum Hydride (LiAlH4)

Lithium aluminum hydride is a powerful reducing agent used in organic synthesis. It can reduce a variety of functional groups, including esters, carboxylic acids, and carbonyls, to their corresponding alcohols. Due to its reactivity, it must be handled under anhydrous conditions and is typically followed by a workup step involving water to quench excess reagent and convert the alkoxide intermediate to an alcohol.

Mechanism of Reduction

The mechanism of reduction with LiAlH4 involves nucleophilic attack by the hydride ion (H-) on the electrophilic carbon of the carbonyl group. This forms a tetrahedral intermediate, which can then collapse to yield an alcohol after protonation. Understanding this mechanism is crucial for predicting the products of reactions involving carbonyl compounds and reducing agents.

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Related Practice

Textbook Question

The two most general amine syntheses are the reductive amination of carbonyl compounds and the reduction of amides. Show how these techniques can be used to accomplish the following syntheses.

(a) benzoic acid → benzylamine

Textbook Question

Reduction of two different carboxylic acid derivatives with LiAlH₄ would give the amine shown. Identify these carboxylic acid derivatives.

Textbook Question

Predict the product of the following reaction sequences.

(b)

Textbook Question

Give the expected products of lithium aluminum hydride reduction of the following compounds (followed by hydrolysis).

(a) butyronitrile

(b) N-cyclohexylacetamide

Textbook Question

Show how each transformation may be accomplished by using a nitrile as an intermediate. You may use any necessary reagents.

(a) hexan-1-ol → heptan-1-amine

Textbook Question

Show how to prepare the following aromatic amines by aromatic nitration, followed by reduction. You may use benzene and toluene as your aromatic starting materials.

(d) m-aminobenzoic acid

Textbook Question

Show how you can synthesize the following compounds starting with benzene, toluene, and alcohols containing no more than four carbon atoms as your organic starting materials. Assume that para is the major product (and separable from ortho) in ortho, para mixtures.

(g) 4-isobutylaniline

Textbook Question

Using any necessary reagents, show how you can accomplish the following multistep syntheses.

(b)

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