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Ch. 19 - Nucleophilic Acyl Substitution II: Carboxylic Acid Derivatives
Mullins - Organic Chemistry: A Learner Centered Approach 1st Edition
Mullins1st EditionOrganic Chemistry: A Learner Centered ApproachISBN: 9780137566471Not the one you use?Change textbook
Chapter 18, Problem 36c

Predict the product of the following reductions.
(c) Chemical structure showing a carbonyl compound with a chlorine atom, and reduction steps using LiAlH4 and H3O+.

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1
Identify the functional groups present in the starting material. The compound contains a ketone group and a chlorine atom attached to the carbon chain.
Recognize the reducing agent used in the reaction. Lithium aluminum hydride (LiAlH₄) is a strong reducing agent, typically used to reduce carbonyl groups to alcohols.
Understand the mechanism of reduction with LiAlH₄. The hydride ion (H⁻) from LiAlH₄ attacks the electrophilic carbon of the carbonyl group, leading to the formation of an alkoxide intermediate.
Consider the role of the second step, which involves quenching with H₃O⁺. This step protonates the alkoxide intermediate, converting it into the corresponding alcohol.
Predict the final product. The ketone group is reduced to an alcohol, while the chlorine atom remains unaffected by LiAlH₄, as it does not reduce halides. The final product is an alcohol with the same carbon skeleton as the starting material.

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Key Concepts

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

Reduction Reactions

Reduction reactions in organic chemistry involve the gain of electrons or hydrogen, or the loss of oxygen by a molecule. These reactions typically convert carbonyl compounds, such as aldehydes and ketones, into alcohols. Understanding the type of reducing agent used, such as lithium aluminum hydride (LiAlH4) or sodium borohydride (NaBH4), is crucial for predicting the products of these reactions.
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Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. In the context of reductions, recognizing the functional groups present, such as carbonyls, alkenes, or nitro groups, helps in predicting the outcome of the reaction. Each functional group reacts differently under reduction conditions, influencing the final product.
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Stereochemistry

Stereochemistry refers to the study of the spatial arrangement of atoms in molecules and how this affects their chemical behavior. In reduction reactions, the stereochemistry of the starting material can influence the stereochemical outcome of the product, especially in cases where chiral centers are involved. Understanding concepts like stereoisomerism and enantiomerism is essential for accurately predicting the products of reductions.
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