Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives

Bruice8th EditionOrganic ChemistryISBN: 9780135213711Not the one you use?Change textbook

Bruice 8th Edition

Ch. 16 - Reactions of Aldehydes and Ketones • More Reactions of Carboxylic Acid Derivatives

Problem 24

Chapter 17, Problem 24

What are the products of the following reactions?
a.
b.
c.
d.

Verified step by step guidance

Step 1: Understand the role of H2 and Raney Ni in these reactions. Raney nickel (Ni) is a catalyst commonly used for hydrogenation reactions. It facilitates the addition of hydrogen (H2) to unsaturated bonds such as double bonds, triple bonds, nitriles, and carbonyl groups.

Step 2: For reaction (a), identify the functional group in the starting material. If the starting material contains a double or triple bond, Raney Ni will catalyze the hydrogenation, converting it to a single bond. For example, an alkene (C=C) will be reduced to an alkane (C-C).

Step 3: For reaction (b), CH3CH2CH2C≡N, recognize that the nitrile group (C≡N) undergoes hydrogenation in the presence of H2 and Raney Ni. This reaction converts the nitrile group into a primary amine (-CH2NH2).

Step 4: For reaction (c), analyze the starting material. If it contains a functional group such as a carbonyl (C=O) or an unsaturated bond, Raney Ni will catalyze its reduction. For example, a ketone (C=O) will be reduced to an alcohol (-CH2OH).

Step 5: For reaction (d), CH3(C=O)OCH3, identify the ester functional group. Under hydrogenation conditions with Raney Ni, the ester can be reduced to an alcohol. Specifically, the ester bond (C=O and C-O) will break, forming two alcohols: one from the carbonyl group and one from the alkoxy group.

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Key Concepts

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

Hydrogenation

Hydrogenation is a chemical reaction that involves the addition of hydrogen (H2) to unsaturated organic compounds, typically alkenes or alkynes, to convert them into saturated hydrocarbons. This process is often facilitated by catalysts such as Raney nickel, which enhances the reaction rate and selectivity. Understanding hydrogenation is crucial for predicting the products of reactions involving unsaturated substrates.

Raney Nickel Catalyst

Raney nickel is a finely divided nickel-aluminum alloy that serves as a highly effective catalyst for hydrogenation reactions. It is particularly useful in reducing carbon-carbon double and triple bonds, as well as in the hydrogenation of functional groups like nitriles and carbonyls. Familiarity with the properties and applications of Raney nickel is essential for understanding its role in the reactions presented.

Functional Group Transformations

Functional group transformations refer to the chemical reactions that convert one functional group into another, altering the reactivity and properties of organic molecules. In the context of the given reactions, recognizing how hydrogenation affects various functional groups, such as nitriles and esters, is vital for predicting the final products. This concept is foundational in organic synthesis and reaction mechanisms.

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Related Practice

Textbook Question

How would you make the following compounds from N-benzylbenzamide?

a. dibenzylamine

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Textbook Question

Why is the pK_a value of protonated hydroxylamine (6.0) so much lower than the value of a protonated primary amine such as protonated methylamine (10.7)?

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Textbook Question

A ketone can be prepared from the reaction of a nitrile with a Grignard reagent. Describe the intermediate formed in this reaction, and show how it can be converted to a ketone.

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Textbook Question

How would you make the following compounds from N-benzylbenzamide?

c. benzyl alcohol

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Textbook Question

The pK_a of protonated acetone is about –7.5 and the pK_a of protonated hydroxylamine is 6.0.

a. In a reaction with hydroxylamine at pH 4.5 (Figure 16.2), what fraction of acetone is present in its acidic, protonated form?

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