Editing Carboxylic acid (section)

=== Reduction ===
Like [[ester]]s, most carboxylic acids can be [[carboxylic acid reduction|reduced]] to alcohols by [[hydrogenation]], or using hydride transferring agents such as [[lithium aluminium hydride]]. Strong alkyl transferring agents, such as [[Organolithium reagent|organolithium]] compounds but not [[Grignard reagents]], will reduce carboxylic acids to ketones along with transfer of the alkyl group.{{cn|date=May 2025}}

The [[Vilsmaier reagent]] (''N'',''N''-Dimethyl(chloromethylene)ammonium chloride; {{chem2|[ClHC\dN+(CH3)2]Cl−}}) is a highly chemoselective agent for carboxylic acid reduction. It selectively activates the carboxylic acid to give the carboxymethyleneammonium salt, which can be reduced by a mild reductant like lithium tris(''t''-butoxy)aluminum hydride to afford an aldehyde in a one pot procedure. This procedure is known to tolerate reactive carbonyl functionalities such as ketone as well as moderately reactive ester, olefin, nitrile, and halide moieties.<ref>{{OrgSynth|title=Reduction of carboxylic acids to aldehydes: 6-Ooxdecanal|prep=CV8P0498|last1=Fujisawa|first1=Tamotsu|last2=Sato|first2=Toshio|collvol=8|collvolpages=498|volume=66|page=121|date=1988|doi=10.15227/orgsyn.066.0121}}</ref>

{{anchor|Barbier-Wieland degradation}}