Ch. 18 - Ketones and Aldehydes

Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook

Wade 9th Edition

Ch. 18 - Ketones and Aldehydes

Problem 39j

Chapter 18, Problem 39j

Predict the major products of the following reactions.
(j)

Verified step by step guidance

Step 1: Analyze the structure of the reactant. The molecule contains a ketone group (C=O) and a primary amine (-NH2) attached to a cyclopentane ring. The reaction involves acidic conditions (H+).

Step 2: Recognize the reaction type. Under acidic conditions, a ketone and a primary amine can undergo a condensation reaction to form an imine. This is known as imine formation.

Step 3: Describe the mechanism. The ketone group will be protonated by H+, increasing its electrophilicity. The amine group will then attack the carbonyl carbon, forming a tetrahedral intermediate.

Step 4: Explain the intermediate steps. The tetrahedral intermediate will lose water (H2O) through a dehydration step, facilitated by the acidic environment, leading to the formation of a double bond between the carbon and nitrogen.

Step 5: Predict the major product. The major product will be an imine, where the nitrogen from the amine is double-bonded to the carbon that was originally part of the ketone group. The cyclopentane ring remains intact.

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Key Concepts

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

Aldehyde Reactivity

Aldehydes are highly reactive due to the presence of a carbonyl group (C=O), which is polarized, making the carbon atom electrophilic. This allows them to readily undergo nucleophilic addition reactions, particularly with amines, leading to the formation of imines or enamines depending on the reaction conditions.

Amine Nucleophilicity

Amines are nucleophiles because they contain a lone pair of electrons on the nitrogen atom, which can attack electrophilic centers such as the carbonyl carbon in aldehydes. The strength of the nucleophilic attack can be influenced by the structure of the amine (primary, secondary, or tertiary) and the reaction conditions, such as the presence of an acid catalyst.

Acid-Catalyzed Reactions

In acid-catalyzed reactions, the presence of an acid (H+) can enhance the electrophilicity of the carbonyl carbon in aldehydes, facilitating the nucleophilic attack by amines. The acid can also protonate the amine, increasing its nucleophilicity and promoting the formation of the product, which in this case is likely an imine.

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Related Practice

Textbook Question

Rank the following carbonyl compounds in order of increasing equilibrium constant for hydration:

CH₃COCH₂Cl ClCH₂CHO CH₂O CH₃COCH₃ CH₃CHO

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Textbook Question

Acetals can serve as protecting groups for 1,2-diols, as well as for aldehydes and ketones. When the acetal is formed from acetone plus the diol, the acetal is called an acetonide. Show the acetonides formed from these diols with acetone under acid catalysis.

Predict the major products of the following reactions.

(g)

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Textbook Question

Predict the major products of the following reactions.