Note: Conversion of a carboxylic acid into a much more reactive acid chloride

Note: Acid chlorides are one of the only carboxylic acid derivatives reactive enough to produce anhydrides by nucleophilic acylation

Note: Dehydrating reagents can condense carboxylic acids into anhydrides

Note: Coupling of carboxylic acids can be especially effective for forming cyclic anhydrides, sometimes only requiring heat

Note: Carboxylic acids can be prepared from more reactive derivatives like acid chlorides by hydrolysis, in this case under basic conditions. Note that the base will deprotonate the resulting carboxylic acid following the primary reaction.

Note: Carboxylic acids can be prepared from more reactive derivatives like anhydrides by hydrolysis, in this case helped by acid catalysis.

Note: Saponification of an ester, driven by base. The exchange of water vs. the ester alcohol should be a reversible equilibrium, but subsequent deprotonation of the resulting carboxylic acid makes this an irreversible reaction.

Note: Acid-catalyzed hydrolysis of an ester to a carboxylic acid, with excess water assumed to drive the reaction equilibrium. Virtually all carboxylic acid derivatives can be hydrolyzed to carboxylic acids with aqueous acid.

Note: Amides are among the least reactive carboxylic acid derivatives. One of the few reactions that can be completed is acid-catalyzed hydrolysis

Warning: Base driven hydrolysis of amides will not work when acid-base reactions can occur first. Even for tertiary amides, hydrolysis is an unlikely result.

Note: Ester preparation from a reactive acid chloride, in this case with a base driven nucleophile

Note: Ester preparation from a reactive anhydride. Note the leftover 'leaving group' from the anhydride.

Warning: Base driven ester preparation will not work against carboxylic acids because acid-base reactions will occur first.

Note: Acid-catalyzed Fischer esterification is the only direct acylation reaction that works for carboxylic acids.

Note: Amide formation from a reactive acid chloride. An extra equivalent of amine or other base is necessary to soak up protons that are produced in the reaction.

Note: Amide formation from a reactive anhydride. An extra equivalent of amine or other base is necessary to soak up protons that are produced in the reaction.

Warning: Amide preparation from a carboxylic acid will not work directly because acid-base reactions will occur first.

Note: DCC (dicyclohexylcarbodiimide) can be used to convert the OH of a carboxylic acid into a good leaving group, making direct amide formation possible.

Note: Amide preparation from an ester is viable, though less reactive than using an acid chloride or anhydride.

Note: The most general way to prepare nitriles is to simply perform an Sn2 substitution with a nitrile ion against an alkyl halide.

Note: Primary amides can be dehydrated to prepare nitriles.

Note: Nitriles are counted among carboxylic acid derivatives in part because they can be hydrolyzed under acid conditions to yield carboxylic acids.

Note: In general, a strong reducing agent like LiAlH4 reduces carboxylic acid derivatives to primary alcohols.

Note: Amides are reduced to amines rather than alcohols.

Note: Nitriles are reduced to primary amines instead of alcohols.

Note: Reduction of nitriles with a milder reducing agent will yield a primary (metallo) imine which will be hydrolyzed down to an aldehyde upon aqueous workup.

Note: Organometallic reagents can add to nitriles to yield a primary (metallo) imine that will be hydrolyzed to a ketone upon aqueous workup.