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Ch. 21 - Carboxylic Acid Derivatives
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
Chapter 21, Problem 39c

Show how each transformation may be accomplished by using a nitrile as an intermediate. You may use any necessary reagents.
(c) octan-1-ol → decan-2-one

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1
Identify the target transformation: The goal is to convert octan-1-ol (an alcohol) into decan-2-one (a ketone). This involves chain elongation by two carbons and functional group transformation.
Convert octan-1-ol into a nitrile intermediate: First, oxidize octan-1-ol to octanal (an aldehyde) using an oxidizing agent like PCC (Pyridinium chlorochromate). Then, perform a nucleophilic addition of HCN (hydrogen cyanide) to the aldehyde to form octanenitrile.
Elongate the carbon chain of the nitrile: React octanenitrile with a Grignard reagent, such as ethylmagnesium bromide (CH₃CH₂MgBr). This step adds two carbons to the chain and forms an imine intermediate.
Hydrolyze the imine intermediate: Treat the imine with aqueous acid (H₃O⁺) to hydrolyze it into decan-2-one, completing the transformation.
Verify the product: Confirm that the final product is decan-2-one, a ketone with a 10-carbon chain and the carbonyl group on the second carbon.

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Key Concepts

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

Nitrile Chemistry

Nitriles are organic compounds containing a cyano group (-C≡N). They can be used as versatile intermediates in organic synthesis, allowing for the formation of various functional groups. In the context of the transformation from octan-1-ol to decan-2-one, nitriles can be formed through the reaction of alcohols with reagents like thionyl chloride or phosphorus pentachloride, followed by nucleophilic addition reactions.
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Reduction Reactions

Reduction reactions involve the gain of electrons or the decrease in oxidation state of a molecule. In organic chemistry, nitriles can be reduced to primary amines or aldehydes using reducing agents such as lithium aluminum hydride (LiAlH4) or hydrogen gas in the presence of a catalyst. Understanding these reduction pathways is crucial for manipulating nitriles to achieve desired carbonyl compounds like decan-2-one.
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Carbon Chain Lengthening

Carbon chain lengthening is a synthetic strategy used to increase the number of carbon atoms in a molecule. This can be achieved through various methods, including the use of nitriles as intermediates. In the transformation from octan-1-ol to decan-2-one, a key step may involve the formation of a longer-chain nitrile, followed by hydrolysis and subsequent reduction to yield the desired ketone, demonstrating the utility of nitriles in building complex organic structures.
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