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Ch. 19 - Amines
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
All textbooksWade 9th EditionCh. 19 - AminesProblem 49a
Chapter 19, Problem 49a

Show how you can synthesize the following tertiary amine three different ways, each using a different secondary amine and adding the final substituent by
(a) reductive amination (3 ways).
Chemical structure of a tertiary amine, showing three different synthesis pathways using secondary amines.

Verified step by step guidance
1
Identify the target tertiary amine structure and determine the substituents that need to be added to a secondary amine to achieve this structure.
For the first method, select a secondary amine that already contains two of the substituents present in the target tertiary amine. Plan to add the third substituent using reductive amination. This involves reacting the secondary amine with an aldehyde or ketone that corresponds to the third substituent, followed by reduction.
For the second method, choose a different secondary amine that contains a different pair of substituents from the target tertiary amine. Again, use reductive amination to add the remaining substituent by reacting with the appropriate aldehyde or ketone, followed by reduction.
For the third method, select yet another secondary amine with a different combination of two substituents. Use reductive amination to introduce the final substituent by reacting with the corresponding aldehyde or ketone, followed by reduction.
In each method, ensure that the reductive amination step is carried out using a suitable reducing agent, such as sodium cyanoborohydride (NaBH3CN), to convert the imine intermediate to the desired tertiary amine.

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Key Concepts

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

Reductive Amination

Reductive amination is a chemical reaction that involves the conversion of a carbonyl compound (like an aldehyde or ketone) into an amine. This process typically includes the formation of an imine or enamine intermediate, which is then reduced to yield the amine. Common reducing agents used in this reaction include sodium cyanoborohydride or lithium aluminum hydride, making it a versatile method for synthesizing amines from carbonyl precursors.
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Tertiary Amines

Tertiary amines are nitrogen-containing compounds where the nitrogen atom is bonded to three carbon atoms. They are typically synthesized from secondary amines through alkylation or reductive amination processes. Tertiary amines are important in organic chemistry due to their unique properties, such as their ability to act as bases and nucleophiles, and they often serve as intermediates in the synthesis of more complex molecules.
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Secondary Amines

Secondary amines are organic compounds where the nitrogen atom is bonded to two carbon atoms and one hydrogen atom. They can be synthesized through various methods, including the reaction of primary amines with alkyl halides or through the reductive amination of carbonyl compounds. Secondary amines are crucial in organic synthesis as they can be further transformed into tertiary amines or other functional groups, making them versatile building blocks in chemical reactions.
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Related Practice
Textbook Question

Several additional amine syntheses are effectively limited to making primary amines. The reduction of azides and nitro compounds and the Gabriel synthesis leave the carbon chain unchanged. Formation and reduction of a nitrile adds one carbon atom. Show how these amine syntheses can be used for the following conversions.

(c) 1-bromo-3-phenylheptane → 3-phenylheptan-1-amine

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Textbook Question

Several additional amine syntheses are effectively limited to making primary amines. The reduction of azides and nitro compounds and the Gabriel synthesis leave the carbon chain unchanged. Formation and reduction of a nitrile adds one carbon atom. Show how these amine syntheses can be used for the following conversions.

(a) allyl bromide → allylamine 

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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.

(b) N-methylbutan-1-amine

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Textbook Question

Show how you can synthesize the following tertiary amine three different ways, each using a different secondary amine and adding the final substituent by (b) acylation–reduction (3 ways).

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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.

(d) cyclohexanone → N-cyclohexylpyrrolidine

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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.

(a) pentan-1-amine

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