Addition of LiAlH4 to ketones to give secondary alcohols

by James

Description: Addition of lithium aluminum hydride to ketones leads to formation of secondary alcohols (after addition of acid) Content available for Reactionguide members only. Not a member? Get access for about 30 cents / day!

{ 4 comments… read them below or add one }

Joseph Delaune

LiAlH4 seems to function in the same alcohol reduction reactions as the reagent, NaBH4. If LiAlH4 achieves the same products as NaBH4, what is the point of having to remember NaBH4 as a reagent?

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Brian Butler

NaBH4 is for selective reduction. For example, if one had a molecule in which a ketone and a carboxylic acid were present and the carboxylic acid was wanted in the final product, one would use NaBH4 because it cannot reduce carboxylic acids (or any derivatives). LiAlH4 is a much stronger reducing agent and would simply convert both of those groups to secondary alcohols.

I hope this helps!

-Brian

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Jason Mathias

On stereochemistry – Since this is a flat structure before AlH3, does this produce equal amounts of enantiomers if there is a stereocenter at the Carbon?

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Andrew David

I’m curious about something. In the protonation step, where does the (seemingly) H3O come from that protonates the O^-? The diagram says we are using H2SO4/H20 so does the H3O happen from the H2SO4/H2O interaction? I’m sorry if this is a stupid question.

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