Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions

Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition

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Mullins 1st Edition

Ch. 10 - Alkynes: Electrophilic Addition and Redox Reactions

Problem 48a

Chapter 9, Problem 48a

Beginning with the molecules on the left, provide a synthesis of the molecule on the right. The ideal number of steps is indicated over the reaction arrow, although there may be alternate routes worth considering.
(a)

Verified step by step guidance

Step 1: Analyze the starting molecule and the target molecule. The starting molecule contains a terminal alkyne group, while the target molecule has an extended carbon chain with a double bond. This suggests that chain elongation and functional group transformation are required.

Step 2: Perform an alkylation reaction on the terminal alkyne. Use a strong base, such as sodium amide (NaNH₂), to deprotonate the terminal alkyne, generating an acetylide ion. Then, react the acetylide ion with an appropriate alkyl halide (e.g., 1-bromo-3-butene) to elongate the carbon chain and introduce the double bond.

Step 3: Verify the stereochemistry of the target molecule. The double bond introduced in the previous step should match the stereochemistry of the target molecule. If necessary, use a stereoselective reaction or adjust the conditions to ensure the correct configuration.

Step 4: Check for any additional functional group transformations. If the target molecule requires further modifications, such as hydrogenation or isomerization, perform the necessary reactions to achieve the desired structure.

Step 5: Confirm the final product matches the target molecule. Compare the structure, stereochemistry, and functional groups to ensure the synthesis is complete and accurate.

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Key Concepts

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

Synthesis in Organic Chemistry

Synthesis in organic chemistry refers to the process of constructing complex organic molecules from simpler ones through a series of chemical reactions. Understanding the target molecule's structure and functional groups is crucial for planning the synthesis route, which often involves multiple steps and specific reagents to achieve the desired transformations.

Reaction Mechanisms

A reaction mechanism describes the step-by-step sequence of elementary reactions by which a chemical change occurs. It provides insight into how reactants are converted into products, including the formation and breaking of bonds, intermediates, and transition states. Familiarity with common mechanisms, such as nucleophilic substitutions or eliminations, is essential for predicting the outcomes of synthetic routes.

Functional Group Transformations

Functional group transformations involve the conversion of one functional group into another, which is a key aspect of organic synthesis. Recognizing the functional groups present in the starting materials and the target molecule allows chemists to select appropriate reactions and reagents that facilitate these transformations, ultimately guiding the synthesis process toward the desired product.

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Related Practice

Textbook Question

Synthesize the following molecules beginning with only organic molecules containing three carbons or fewer.

(b)

982

views

Textbook Question

Suggest a method for synthesizing the following alkynes using an alkyne and an alkyl halide. [There are two correct answers for each product.]

(c)

867

views

Textbook Question

Beginning with the molecules on the left, provide a synthesis of the molecule on the right. The ideal number of steps is indicated over the reaction arrow, although there may be alternate routes worth considering.

(b)

924

views

Textbook Question

Suggest a method for synthesizing the following alkynes using an alkyne and an alkyl halide. [There are two correct answers for each product.]

(a)

1004

views

Textbook Question

Synthesize the following molecules beginning with only organic molecules containing three carbons or fewer.

(e)

988