Ch.10 - Structure and Synthesis of Alcohols

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

Wade 9th Edition

Ch.10 - Structure and Synthesis of Alcohols

Problem 57c,d

Chapter 10, Problem 57c,d

Show how this 1° alcohol can be made from the following:

(c) a 7-carbon aldehyde
(d) a carboxylic acid

Verified step by step guidance

Step 1: Identify the target molecule, which is a primary alcohol with a cyclopentyl group attached to a 2-carbon chain ending in a hydroxyl group (-OH).

Step 2: For part (c), starting from a 7-carbon aldehyde, use a reduction reaction. The aldehyde can be reduced to a primary alcohol using a reducing agent such as sodium borohydride (NaBH₄) or lithium aluminum hydride (LiAlH₄). Write the reaction as:

R_{2} - C = O + H {NaBH}_{4} \to R_{2} - CH - OH

Step 3: For part (d), starting from a carboxylic acid, first convert the carboxylic acid to an aldehyde. This can be achieved using a mild reducing agent such as DIBAL-H (diisobutylaluminum hydride) under controlled conditions. Write the reaction as:

R - COOH + DIBAL \to R - CHO

Step 4: After obtaining the aldehyde from the carboxylic acid, proceed with the reduction step as described in Step 2 to convert the aldehyde into the primary alcohol.

Step 5: Verify the structure of the final product to ensure it matches the target molecule, confirming that the cyclopentyl group and the hydroxyl group are correctly positioned.

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Key Concepts

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

Alcohol Synthesis

Alcohols can be synthesized through various methods, including reduction reactions. A primary (1°) alcohol can be formed by reducing an aldehyde or a carboxylic acid. Understanding the reduction process, which involves the addition of hydrogen or the removal of oxygen, is crucial for converting carbonyl compounds into alcohols.

Aldehyde Reduction

Aldehydes can be reduced to primary alcohols using reducing agents such as lithium aluminum hydride (LiAlH4) or sodium borohydride (NaBH4). This reaction involves the nucleophilic attack of the hydride ion on the carbonyl carbon, leading to the formation of the alcohol. Recognizing the structure and reactivity of aldehydes is essential for this transformation.

Carboxylic Acid Reduction

Carboxylic acids can be reduced to primary alcohols through a similar process, typically requiring stronger reducing agents like LiAlH4. The reduction involves the conversion of the carboxyl group (-COOH) to a hydroxyl group (-OH), resulting in the formation of a primary alcohol. Understanding the mechanism of this reduction is vital for synthesizing alcohols from carboxylic acids.

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Related Practice

Textbook Question

For each synthesis, start with bromocyclohexane and predict the products. Assume that an excess of each reactant is added so that all possible reactions that can happen will happen.

(a)

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Textbook Question

For each synthesis, start with bromocyclohexane and predict the products. Assume that an excess of each reactant is added so that all possible reactions that can happen will happen.

(b)

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Textbook Question

Show how this 1° alcohol can be made from the following:

(a) a 1° alkyl bromide

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Textbook Question

Often, compounds can be synthesized by more than one method. Show how this 3° alcohol can be made from the following:

(d) a 3° alkyl bromide

Textbook Question

Show how this 1° alcohol can be made from the following:

(e) an alkene