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14.13: Acid Halides to Alcohols: LiAlH4 Reduction

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Organic Chemistry

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Acid Halides to Alcohols: LiAlH4 Reduction

14.13: Acid Halides to Alcohols: LiAlH4 Reduction

Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.

The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as the final product.


However, it is possible to stop the reaction at the aldehyde by using a milder reducing agent like diisobutylaluminum hydride or lithium tri(t-butoxy)aluminum hydride.


Acid Halides Alcohols LiAlH4 Reduction Strong Reducing Agent Lithium Aluminum Hydride Mechanism Nucleophilic Hydride Ion Carbonyl Carbon Tetrahedral Intermediate Carbonyl Group Leaving Group Aldehyde Nucleophilic Attack Alkoxide Ion Protonation Primary Alcohol Milder Reducing Agent Diisobutylaluminum Hydride Lithium Tri(t-butoxy)aluminum Hydride

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